C:\WINWORD\CCITTREC.DOT_______________

	A.129	user agent (UA)

F: agent d'usager (AU)

S: agente de usuario (AU)

	In the context of message handling, the functional object, a component of 
MHS, by means of which a single direct user engages in message handling.

	Component of MHS the user interacts with.

ANNEX B

(to Recommendation X.400)

Definitions of elements of service

	Note – The abbreviations used in the title lines have the following meanings:

	TM		Message transfer

	IPM		Interpersonal messaging

	PD		Physical delivery

	MS		Message store

	PR		Per recipient (available on a per–recipient basis)

B.1		Access 
management	TM

	This element of service enables a UA and MTA to establish access to 
one another and to manage information associated with access establish-
ment.

	The element of service permits the UA and MTA to identify and vali-
date the identity of the other. It provides a capability for the UA to specify 
its O/R address and to maintain access security. When access security is 
achieved through passwords, these passwords can be periodically updated.

	Note – A more secure form of access management is provided by the 
element of service secure access management.

B.2		Addi-
tional physical rendition	PD	PR

	This element of service allows an originating user to request the 
PDAU to provide the additional renditon facilities (e.g., kind of paper, 
colour printing, etc.). Bilateral agreement is required to use this element of 
service.

B.3		Alter-
nate recipient allowed	MT

	This element of service enables an originating UA to specify that the 
message being submmitted can be delivered to an alternate recipient as 
described below.

	A destination MD will interpret all of the user attributes in order to 
select a recipient UA. Three cases can be distinguished:

1)	all the attributes match precisely those of a subscriber UA. Delivery 
is attempted to that UA;

2)	either insufficient attributes are supplied or those supplied match 
those of more than one subscriber UA. The message cannot be 
delivered;

3)	at least the minimum set of attributes required by the destination 
MD is supplied. Nevertheless, taking all of the other attributes into 
account, the attributes match those of no UA.

	In case 3, an MD that supports the alternate recipient assignment element of 
service can deliver the message to a UA that has been assinged to receive 
such messages. This UA will be notified of the O/R address of the intended 
recipient as specified by the originator. Delivery to this UA will be reported 
in a delivery notification if requested by the originator.

B.4		Alter-
nate recipient assignment	MT

	This element of service enables a UA to be given the capability to 
have certain messages delivered to it for which there is not an exact match 
between the recipient attributes specified and the name of the user. Such a 
UA is specified in terms of one or more attributes for which an exact match 
is required, and one or more attributes for which any value is acceptable. For 
example, an orginization can establish a UA to receive all messages for 
which country name, administration management domain name and organi-
zation name (for example, company name) are an exact match but the per-
sonal name of the recipient does not correspond to an individual known by 
an MHS in that organization. This permits the organization to manually han-
dle the messages to these individuals.

	In order for a message to be reassigned to an alternate recipient, the 
originator must have requested the alternate recipient allowed element of 
service.

B.5		Autho-
rizing users indication	IPM

	This element of service allows the originator to indicate to the recipi-
ent the names of the one or more persons who authorized the sending of the 
message. For example, an individual can authorize a particular action which 
is subsequently communicated to those concerned by another person such as 
a secretary. The former person is said to authorize its sending while the lat-
ter person is the one who sent the message (originator). This does not imply 
signature-level authorization.

B.6		Auto–
forwarded indication	IPM

	This element of service allows a recipient to determine that a body of 
an incoming IP–message contains an IP–message that has been auto–for-
warded. Thus the recipient can distinguish from that where an incoming 
IP-message contains a forwarded message (as described in § B–31) in the 
body. As with a forwarded IP–message, an auto–forwarded IP–message can 
be accompanied by information (for example, time stamps, indication of 
conversion) associated with its original delivery.

	Note – The indication that auto–forwarding of an IP–message has 
occurred enables a recipient IPM UA, should it so choose, to prevent further 
auto–forwarding and thus the possibility of loops. In addition, a recipient 
IPM UA can choose whether or not to auto–forward based on other criteria 
(for example, sensitivity classification).

	When an IPM UA auto–forwards an IP–message, it designates it as 
auto–forwarded. If receipt/non–receipt notification has been requested for 
the IP–message being auto–forwarded, the IPM UA generates a non–receipt 
notification informing the originator of the auto–forwarding of the IP–mes-
sage. The notification optionally includes a comment supplied by the origi-
nally intended recipient. No further notification applying to the auto–
forwarded IP-message is generated by any IPM UA.

B.7		Basic 
physical rendition	PD	PR

	This element of service enables the PDAU to provide the basic rendi-
ton facilities for converting the MHS message into a physical message. This 
is the default action to be taken by the PDAU.

B.8		Blind 
copy recipient indication	IPM	PR

	This element of service allows the originator to provide the O/R name 
of one or more additional users, or DLs, who are intended recipients of the 
IP–message being sent. These names are not disclosed to either the primary 
or copy recipients. Whether or not these additional recipients are disclosed 
to one another is a local matter.

B.9		Body 
part encryption indication	IPM

	This element of service allows the originator to indicate to the recipi-
ent that a particular body of the IP-message being sent has been encrypted. 
Encryption can be used to prevent unauthorized inspection or modification 
of the body part. This element of service can be used by the recipient to 
determine that some body part(s) of the IP-message must be decrypted. This 
element of service, however, does not itself encrypt or decrypt any body 
part.

B.10		Content 
confidentiality	MT

	This element of service allows the originator of a message to protect 
the content of the message from disclosure to recipients other than the 
intended recipient(s). Content confidentiality is on a per–message basis, and 
can use either an asymmetric or a symmetric encryption technique.

B.11		Content 
integrity	MT	PR

	This element of service allows the originator of the message to pro-
vide to the recipient of the message a means by which the recipient can ver-
ify that the content of the message has not been modified. Content integrity 
is on a per–recipient basis, and can use either an asymmetric or a symmetric 
encryption technique.

B.12		Content 
type indication	MT

	This element of service enables an originating UA to indicate the con-
tent type for each submitted message. A recipient UA can have one or more 
content types delivered to it. An example of a content type is the contents 
generated by the IPM class of cooperating UAs.

B.13		Conver-
sion prohibition	MT

	This element of service enables an originating UA to instruct the MTS 
that implicit encoded information type conversion(s) should not be per-
formed for a particular submitted message.

B.14		Conver-
sion prohibition in case of loss of information	MT

	This element of service enables an originating UA to instruct the MTS 
that encoded information type conversion(s) should not be performed for a 
particular submitted message if such conversion(s) would result in loss of 
information. Loss of information is discussed in detail in X.408.

	Should this and the conversion prohibition element of service both be 
selected, the latter shall take precedence.

	Note – This element of service will not protect against possible loss of 
information in certain cases where the recipient is using an I/O device 
whose capabilities are unknown to the MTA.

B.15		Con-
verted indication	MT	PR

	This element of service enables the MTS to indicate to a recipient UA 
that the MTS performed encoded information type conversion on a deliv-
ered message. The recipient UA is informed of the resulting types.

B.16		Counter 
collection	PD	PR

	This element of service allows an originating user to instruct the PDS 
to keep the physical message ready for counter collection at the post office 
specified by the originator, or at the post office which offers counter collec-
tion service closest to the given recipient's address.

B.17		Counter 
collection with advice	PD	PR

	This element of service allows an originating user to instruct the PDS 
to keep the physical message ready for counter collection at the post office 
specified by the originator, or at the post office which offers counter collec-
tion service closest to the given recipient's address, and to inform the recipi-
ent via telephone, or telex, or teletex, using the number provided by the 
originator.

B.18		Cross–
referencing indication	IPM

	This element of service allows the originator to associate with the IP–
message being sent, the globally unique identifiers of one or more other IP–
messages. This enables the recipient's IPM UA, for example, to retrieve 
from storage a copy of the referenced IP–messages.

B.19		Deferred 
delivery	MT

	This element of service enables an originating UA to instruct the MTS 
that a message being submitted shall be delivered no sooner than a specified 
data and time. Delivery will take place as close to the date and time speci-
fied as possible, but not before. The date and time specified for deferred 
delivery is subject to a limit which is defined by the originator's manage-
ment domain.

	Note – Storage of the message shall be handled in the originating 
country.

B.20		Deferred 
delivery cancellation	MT

	This element of service enables an originating UA to instruct the MTS 
to cancel a previously submitted deferred delivery message. The cancella-
tion attempt may or may not always succeed. Possible reasons for failure 
are: deferred delivery time has passed, or the message has already been for-
warded within the MTS.

B.21		Delivery 
notification	MT	PR

	This element of service enables an originating UA to request that the 
originating UA be explicitly notified when a submitted message has been 
successfully delivered to a recipient UA or access unit. The notification is 
related to the submitted message by means of the message indentifier and 
includes the date and time of delivery. In the case of a multi–destination 
message, the originating UA can request this element of service or a per–
recipient basis.

	When a message is delivered after distribution list expansion, then, 
depending on the policy of the distribution list, the notification can be sent 
to either the list owner, the message originator, or both.

	Delivery notification carries no implication that any UA or user 
action, such as examination of the message content, has taken place.

B.22		Delivery 
time stamp indication	MT	PR

	This element of service enables the MTS to indicate to a recipient UA 
the date and time at which the MTS delivered a message. In the case of 
physical delivery, this element of service indicates the date and time at 
which the PDAU has taken responsibility for printing and further delivery of 
the physical message.

B.23		Delivery 
via bureaufax service	PD	PR

	This element of service allows an originating user to instruct the 
PDAU and associated PDS to use the bureaufax service for transport and 
delivery.

B.24		Designa-
tion of recipient by directory name	MT	PR

	This element of service enables an originating UA to use a directory 
name in place of an individual recipient's O/R address.

B.25		Disclo-
sure of other recipients	MT

	This element of service enables the originating UA to instruct the 
MTS then submitting a multi–recipient message, to disclose the O/R names 
of all other recipients to each recipient UA, upon delivery of the message. 
The O/R names disclosed are as supplied by the originating UA. If distribu-
tion list expansion has been performed, then only the originator specified 
DL name will be disclosed, and not the names of its members.

B.26		DL 
expansion history indication	MT

	This element of service provides to a recipient, at delivery, informa-
tion about the distribution list(s) through which the message has arrived. It is 
a local matter as to how much of this information is presented to the recipi-
ent.

B.27		DL 
expansion prohibited	MT

	This element of service allows an originating user to specify that if 
any of the recipients can directly or via reassignment refer to a distribution 
list, then no expansion shall occur. Instead, a non–delivery notification will 
be returned to the originating UA, unless prevention of non–delivery notifi-
cation has been requested.

B.28		EMS 
(express mail service)	PD	PR

	This element of service allows an originating user to instruct the PDS 
to transport and deliver the physical message produced from the MHS mes-
sage through accelerated letter circulation and delivery service (such as 
EMS or the equivalent domestic service) in the destination country.

B.29		Expiry 
date indication	IPM

	This element of service allows the originator to indicate to the recipi-
ent the date and time after which he considers the IP–message to be invalid. 
The intent of this element of service is to state the originator's assessment of 
the current applicability of an IP–message. The particular action on behalf 
of a recipient by his IPM UA, or by the recipient himself, is unspecified. 
Possible actions might be to file or delete the IP–message after the expiry 
date has passed.

B.30		Explicit 
conversion	MT	PR

	This element of service enables an originating UA to request the MTS 
to perform a specified conversion, such as required when interworking 
between different telematic services. When a message is delivered after con-
version has been performed, the recipient UA is informed of the original 
encoded information types as well as the current encoded information types 
in the message.

	Note 1 – This element of service is intended to support interworking 
with telematic terminals/services.

	Note 2 – When DL names are used in conjunction with this element 
of service, conversion will apply to all members of the DL.

B.31		For-
warded IP–message indication	IPM

	This element of service allows a forwarded IP–message, or a for-
warded IP–message plus its “delivery information” to be sent as the body 
(or as one of the body parts) of an IP–message. An indication that the body 
part is forwarded is conveyed along with the body part. In a multi–part body, 
forwarded body parts can be included along with body parts of other types. 
“Delivery information” is information which is conveyed from the MTS 
when an IP-message is delivered (for example, time stamps and indication 
of conversion). However, inclusion of this delivery information along with a 
forwarded IP–message in no way guarantees that this delivery information 
is validated by the MTS.

	The receipt notification request indication and the non–receipt notifi-
cation request elements of service are not affected by the forwarding of a 
IP–message.

B.32		Grade of 
delivery selection	MT

	This element of service enables an originating UA to request that 
transfer through the MTS be urgent or non-urgent, rather than normal. The 
time periods defined for non–urgent and urgent transfer are longer and 
shorter, respectively, than that defined for normal transfer. This indication is 
also sent to the recipient with the message.

B.33		Hold for 
delivery	MT

	This element of service enables a recipient UA to request that the 
MTS hold its messages and returning notifications for delivery until a later 
time. The UA can indicate to the MTS when it is unavailable to take delivery 
of messages and notifications, and also, when it is again ready to accept 
delivery of messages and notifications from the MTS. The MTS can indicate 
to the UA that messages are waiting due to the criteria the UA established 
for holding messages. Responsibility for the management of this element of 
service lies with the recipient MTA.

	Criteria for requesting a message to be held for delivery are: encoded 
information type, content type, maximum content length, and priority. The 
message will be held until the maximum delivery time for that message 
expires, unless the recipient releases the hold prior to its expiry.

	Note – The hold for delivery element of service is distinct from the 
message store facility. The hold for delivery element of service provides 
temporary storage to facilitate delivery and only after a message has been 
transferred to the recipient's UA, is delivery notification returned. The mes-
sage store facility augments the storage of a UA and can be used to store 
messages for an extended period of time. Unlike the hold for delivery ele-
ment of service, delivery notifications are returned as soon as the message is 
placed in (that is, delivered to) the message store.

B.34		Implicit 
conversion	MT

	This element of service enables a recipient UA to have the MTS per-
form for a period of time any necessary conversion on messages prior to 
delivery. Neither the originating nor recipient UA explicitly requests this 
element of service on a per–message basis. If the encoded information type 
capabilities of the recipient UA are such that more than one type of conver-
sion can be performed, the most appropriate conversion is performed. When 
a message is delivered after conversion has been performed, the recipient 
UA is informed of the original encoded information types as well as the cur-
rent encoded information types in the message.

B.35		Impor-
tance indication	IPM

	This element of service allows the originator to indicate to the recipi-
ents his assessment of the importance of the IP–message being sent. Three 
levels of importance are defined: low, normal, and high.

	This element of service is not related to the grade of delivery selection 
element of service provided by the MTS. The particular action taken by the 
recipient or his IPM UA based on the importance categorization is unspeci-
fied. It is the intent to allow the recipient IPM UA, for example, to present 
IP–messages in order of their importance or to alert the recipient of the 
arrival of IP–messages of high importance.

B.36		Incom-
plete copy indication	IPM

	This element of service allows an originator to indicate that this IP–
message is an incomplete copy of an IP-message with the same IP–message 
identification in that one or more body parts, and/or heading fields of the 
original IP–message are absent.

B.37		IP–mes-
sage identification	IPM

	This element of service enables cooperating IMP UAs to convey a 
globally unique identifier for each IP-message sent or received. The IP–
message identifier is composed of an O/R name of the originator and an 
identifier that is unique with respect to that name. IPM UAs and users use 
this identifier to refer to a previously sent or received IP–message (for 
example, in receipt notifications).

B.38		Lan-
guage indication	IPM

	This element of service enables an originating UA to indicate the lan-
guage type(s) of a submitted IP-message.

B.39		Latest 
delivery designation	MT

	This element of service enables an originating UA to specify the latest 
time by which the message is to be delivered. If the MTS cannot deliver by 
the time specified, the message is not delivered and is cancelled. On 
multi-recipient messages, the latest delivery time can expire prior to deliv-
ery to all recipients, but this will not negate any deliveries which have 
already occurred.

B.40		Message 
flow confidentiality	MT

	This element of service allows the originator of the message to protect 
information which might be derived from observation of the message flow.

	Note – Only a limited form of this is supported.

B.41		Message 
identification	MT

	This element of service enables the MTS to provide a UA with a 
unique identifier for each message or probe submitted or delivered by the 
MTS. UAs and the MTS use this identifier to refer to a previously submitted 
message in connection with elements of service such as delivery and non–
delivery notification.

B.42		Message 
origin authentication	MT	PR

	This element of service allows the originator of a message to provide 
to the recipient(s) of the message, and any MTA through which the message 
is transferred, a means by which the origin of the message can be authenti-
cated (i.e. a signature). Message origin authentication can be provided to the 
recipient(s) of the message, and any MTA through which the message is 
transferred, on a per–message basis using an asymmetric encryption tech-
nique, or can be provided only to the recipient(s) of the message, on a per–
recipient basis using either an asymmetric or a symmetric encryption tech-
nique.

B.43		Message 
security labelling	MT

	This element of service allows the originator of a message (or probe) 
to associate with the message (and any reports on the message or probe) an 
indication of the sensitivity of the message (a security label). The message 
security label may be used by the MTS and the recipient(s) of the message 
to determine the handling of the message in line with the security policy in 
force.

B.44		Message 
sequence integrity	MT	PR

	This element of service allows the originator of the message to pro-
vide to a recipient of the message a means by which the recipient can verify 
that the sequence of messages from the originator to the recipient has been 
preserved (without message loss, re–ordering, or replay). Message sequence 
integrity is on a per–recipient basis, and can use either an asymmetric or a 
symmetric encryption technique.

B.45		Multi–
destination delivery	MT	PR

	This element of service enables an originating UA to specify that a 
message being submitted is to be delivered to more than one recipient UA. 
Simultaneous delivery to all specified UAs is not implied by this element of 
service.

B.46		Multi–
part body	IPM

	This element of service allows an originator to send to a recipient or 
recipients an IP–message with a body that is partitioned into several parts. 
The nature and attributes, or type, of each body part are conveyed along with 
the body part.

B.47		Non–
delivery notification	MT	PR

	This element of service enables the MTS to notify an originating UA 
if a submitted message was not delivered to the specified recipient UA(s). 
The reason the message was not deliverd is included as part of the notifica-
tion. For example, the recipient UA can be unknown to the MTS.

	In the case of a multi–destination message, a non–delivery notifica-
tion can refer to any or all of the recipient UAs to which the message could 
not be delivered.

	When a message is not delivered after distribution list expansion, 
then, depending on the policy of the distribution list, the notification can be 
sent to either the list owner, the message originator, or both.

B.48		Non–
receipt notification request indication	IPM	PR

	This element of service allows the originator to ask that he be notified 
should the IP–message be deemed unreceivable. In the case of a multi–
recipient IP–message, the originator can request this element of service on a 
per-recipient basis.

	The originator's UA conveys his request to the recipient's UA. The 
recipient's UA automatically issues a non-recipient notification when any of 
the following events occur:

1)	the recipient's UA auto–forwards the IP–message to another user;

2)	the recipient's UA discards the IP–message prior to receipt;

3)	the recipient's subscription is terminated before he receives the IP–
message.

	Since receipt can occur arbitrarily long after delivery, the recipient's failure 
to access the IP–message, even for a long period of time (for example, while 
on an extended business trip), does not constitute non–receipt and thus no 
notification is issued.

	Note – No legal significance can be adduced from this element of service.

B.49		Non–
repudiation of delivery	MT	PR

	This element of service allows the originator of a message to obtain 
from the recipient(s) of the message irrevocable proof that the message was 
delivered to the recipient(s). This will protect against any attempt by the 
recipient(s) to subsequently deny receiving the message or its content. Non–
repudiation of delivery is provided to the originator of a message on a per–
recipient basis using asymmetric encryption techniques.

B.50		Non–
repudiation of origin	MT	PR

	This element of service allows the originator of a message to provide 
the recipient(s) of the message irrevocable proof of the origin of the mes-
sage. This will protect against any attempt by the originator to subsequently 
revoke the message or its content. Non–repudiation of origin is provided to 
the recipient(s) of a message on a per-message basis using asymmetric 
encryption techniques.

B.51		Non–
repudiation of submission	MT

	This element of service allows the originator of a message to obtain 
irrevocable proof that a message was submitted to the MTS for delivery to 
the originally specified recipient(s). This will protect against any attempt by 
the MTS to subsequently deny that the message was submitted for delivery 
to the originally specified recipient(s). Non-repudiation of submission is 
provided to the originator of a message on a per–message basis, and uses an 
asymmetric encryption technique.

B.52		Obsolet-
ing indication	IPM

	This element of service allows the originator to indicate to the recipi-
ent that one or more IP–messages he sent previously are obsolete. The IP–
message that carries this indication supersedes the obsolete IP–message.

	The action to be taken by the recipient or his IPM UA is a local mat-
ter. The intent, however, is to allow the IPM UA or the recipient to, for 
example, remove or file obsolete messages.

B.53		Ordi-
nary mail	PDPR

	This element of service enables the PDS to transport and deliver the 
letter produced from the MHS message in the mode available through the 
ordinary letter mail service in the country of destination. This is the default 
action for the transport and delivery of a physical message.

B.54		Original 
encoded information types indication	MT

	This element of service enables an originating UA to specify to the 
MTS the encoded information types of a message being submitted. When 
the message is delivered, it also indicates to the recipient UA the encoded 
information types of the message specified by the originating UA.

B.55		Oriniga-
tor indication	IPM

	This element of service allows the identity of the originator to be con-
veyed to the recipient. The intent of this IPM element of service is to iden-
tify the originator in a user–friendly way. In contrast, the MTS provides to 
the recipient the actual O/R address and directory name, if present, of the 
originator. DL names should not be used in originator indication.

B.56		Origina-
tor requested alternate recipient	MT	PR

	This element of service enables an originating UA to specify, for each 
intended recipient, one alternate recipient to which the MTS can deliver the 
message, if delivery to the intended recipient is not possible. The alternate 
recipient can be a distribution list. For the purposes of determining success 
or failure (and hence delivery and non-delivery notifications), delivery to the 
originator requested alternate recipient is equivalent to delivery to the 
intended recipient. If the intended recipient has requested redirection of 
incoming messages, and if the originating UA has requested redirection 
allowed by the originator, the system first tries to redirect the message. If 
this fails, the system then attempts to deliver the message to the designated 
alternate recipient.

B.57		Physical 
delivery notification by MHS	PD	PR

	This element of service allows an originating user to request that an 
explicit notification, informing the originator of either successful or unsuc-
cessful delivery of the physical message, be generated and returned by 
MHS. The notification provides information on delivery but no physical 
record is provided by the PDS.

	Note 1 – The notification includes the date and time of delivery based 
on the delivery confirmation given by the delivery person, the addressee or 
another authorized person. This is subject to national regulations in the des-
tination contry and is also dependent on the type of delivery requested (e.g., 
in the case of registered mail to addressee in person, the addressee would be 
the confirming person).

	Note 2 – This notification carries no implication that any action on the 
part of the recipient (such as examination of the message content) has taken 
place.

	Note 3 – When this element of service is requested, and the physical 
message is undeliverable, it is either returned or destroyed depending on 
national regulations in the destination country, which means that the default 
action of the element of service B.91 is overridden.

B.58		Physical 
delivery notification by PDS	PD	PR

	This element of service allows an originating user to request that an 
explicit notification, informing the originator of either successful or unsuc-
cessful delivery of the physical message, be generated and returned by the 
PDS. The notification serves as a record of delivery for the originating user 
to retain for reference.

	Note 1 – The notification includes the date and time, and, in the case 
of successful delivery, the signature of the person confirming the delivery. 
The confirming person can be the delivery person, the addressee or another 
authorized person. This is subject to national regulations in the destination 
country and is also dependent on the type of delivery requested (e.g., in the 
case of registered mail to addressee in person, the addressee would be the 
confirming person).

	Note 2 – This notification carries no implication that any action on the 
part of the recipient (such as examination of the message content) has taken 
place.

	Note 3 – When this element of service is requested, and the physical 
message is undeliverable, is either returned or destroyed depending on 
national regulations in the destination country, which means that the default 
action of the element of service B.91 is overridden.

B.59		Physical 
forwarding allowed	PD	PR

	This element of service enables the PDS to forward the physical mes-
sage to a forwarding address if the recipient has changed his address and 
indicated this to the PDS. This is the default action taken by the PDS.

B.60		Physical 
forwarding prohibited	PD	PR

	This element of service allows an originating user to instruct the PDS 
not to forward the physical message to a forwarding address.

B.61		Preven-
tion of non–delivery notification	MT	PR

	This element of service enables an originating UA to instruct the MTS 
not to return a non–delivery notification to the originating UA in the event 
that the message being submitted is judged undeliverable. In the case of a 
multi–destination message, the originating UA can request this element of 
service on a per–recipient basis.

B.62		Primary 
and copy recipients indication	IPM

	This element of service allows the originator to provide the names of 
zero or more users, or DLs, who are the intended primary recipients of the 
IP–message, and the names of zero or more users, or DLs, who are the 
intended copy recipients of the IP–message. It is intended to enable a recipi-
ent to determine the category in which each of the specified recipients 
(including the recipient himself) was placed. The exact distinction between 
these two categories of recipients is unspecified. However, the primary 
recipients, for example, might be expected to act upon the IP-message, 
while the copy recipients might be sent the IP–message for information 
only.

	Note – As an example of this element of service in a typical memo-
randum, the primary recipients are normally designated by the directive 
“to:” while “cc:” identifies the copy recipients.

B.63		Probe	
MT

	This element of service enables a UA to establish before submission 
whether a particular message could be delivered. The MTS provides the 
submission information and generates delivery and/or non–delivery notifi-
cations indicating whether a message with the same submission information 
could be delivered to the specified recipient UAs.

	The probe element of service includes the capability of checking 
whether the content size, content type, and/or encoded information types 
would render it undeliverable. The significance of the result of a probe 
depends upon the recipient UA(s) having registered with the MTS the 
encoded information types, content type and maximum message size that it 
can accept. This element of service is subject to the same delivery time tar-
gets as for the urgent class. In the case of DLs, a probe indicates nothing 
about the likelihood of successful delivery to the DL members, but only 
whether the originator has the right to submit to the DL.

B.64		Probe 
origin authentication	MT

	This element of service allows the originator of a probe to provide to 
any MTA through which the probe is transferred a means to authenticate the 
origin of the probe (i.e. a signature). Probe origin authentication is on a per–
probe basis, and uses an asymmetric encryption technique.

B.65		Proof of 
delivery	MT	PR

	This element of service allows the originator of a message to obtain 
from the recipient(s) of the message the means to authenticate the identity of 
the recipient(s) and the delivered message and content. Message recipient 
authentication is provided to the originator of a message on a per–recipient 
basis using either symmetric or asymmetric encryption techniques.

B.66		Proof of 
submission	MT

	This element of service allows the originator of a message to obtain 
from the MTS the means to authenticate that the message was submitted for 
delivery to the originally intended recipient. Message submission authenti-
cation is provided on a per–message basis, and can use symmetric or asym-
metric encryption techniques.

B.67		Receipt 
notification request indication	IPM	PR

	This element of service allows the originator to ask that he be notified 
when the IP–message being sent is received. In the case of a multi–recipient 
message, the originator can request this element of service on a per-recipient 
basis. This element of service also implicitly requests non–receipt notifica-
tion request indication.

	The originator's UA conveys his request to the recipient's UA. The 
recipient can instruct his UA to honour such requests, either automatically 
(for example, when it first renders the IP–message on the recipient's termi-
nal) or upon his explicit command. The recipient can also instruct his UA, 
either in blanket fashion or case by case, to ignore such requests.

B.68		Redirec-
tion disallowed by originator	MT

	This element of service enables an originating UA to instruct the 
MTS, if the recipient has requested the redirection of incoming messages 
element of service, that redirection should not be applied to a particular sub-
mitted message.

B.69		Redirec-
tion of incoming messages	MT

	This element of service enables a UA to instruct the MTS to redirect 
incoming messages addressed to it, to another UA or to a DL, for a specified 
period of time, or until revoked.

	Note 1 – This is an MT element of service that does not necessitate 
delivery to the intended recipient before redirection can take place. It is 
therefore distinct from the IPM Auto–Forwarded Indication Element of Ser-
vice.

	Note 2 – When security provisions are in force, different incoming 
messages, on the basis of their security labels, may be redirected to separate 
alternate recipients or not re–directed at all.

B.70		Regis-
tered mail	PD	PR

	This element of service allows an originating user to instruct the PDS 
to handle the physical message as registered mail.

B.71		Regis-
tered mail to addressee in person	PD	PR

	This element of service allows an originating user to instruct the PDS 
to handle the physical message as registered mail and to deliver it to the 
addressee only.

B.72		Reply 
request indication	IPM	PR

	This element of service allows the originator to request that a recipi-
ent send an IP–message in reply to the IP-message that carries the request. 
The originator can also specify the date by which any reply should be sent, 
and the one or more users and DLs to whom the originator requests (but 
does not demand) be among the preferred recipients of any reply. The recip-
ient is informed of the date and names but it is up to the recipient to decide 
whether or not, and if so, to whom to reply.

	Note – A blind copy recipient should consider carefully to whom he 
sends a reply, in order that the meaning of the blind copy recipient indica-
tion element of service is preserved.

B.73		Reply-
ing IP–message indication	IPM

	This element of service allows the originator of an IP–message to 
indicate to the recipient(s) that this IP-message is being sent in reply to 
another IP–message. A reply can, depending on the wishes of the originator 
of the replied–to message, and the final decision of the originator of the 
reply, be sent to:

1)	the recipients specified in the reply request indication of the 
replied–to message;

2)	the originator of the replied–to message;

3)	the originator and other recipients;

4)	a distribution list, in which the originator of the replied–to message 
can be a receiving member;

5)	other recipients as chosen by the originator of the reply.

	The recipients of the reply receive it as a regular IP–message, together with 
an indication of which IP-message it is a reply to.

B.74		Report 
origin authentication	MT

	This element of service allows the originator of a message (or probe) 
to authenticate the origin of a report on the delivery or non–delivery of the 
subject message (or probe), (a signature). Report origin authentication is on 
a per-basis, and uses an asymmetric encryption technique.

B.75		Request 
for forwarding address	PD	PR

	This element of service allows an originating user to instruct the PDS 
to provide the forwarding address if the recipient has changed his address 
and indicated this to the PDS.

	This element of service can be used with either physical forwarding 
allowed or prohibited. The provision of the forwarding address by the PDS 
to an originating user is subject to national regulations in the destination 
country. The default action is no provision of the forwarding address.

B.76		
Requested delivery method	MT	PR

	This element of service allows a user to request, on a per–recipient 
basis, the preference of method or methods of message delivery (such as 
through an access unit). Non–delivery results if preference(s) cannot be sat-
isfied.

B.77		
Restricted delivery	MT

	This element of service enables a recipient UA to indicate to the MTS 
that it is not prepared to accept delivery of messages from certain originat-
ing UAs or DLs.

	Note 1 – This element of service can be requested in either of two 
ways:

a)	specification by the recipient UA of unauthorized originators, all 
other originators are considered as authorized;

b)	specification by the recipient UA of authorized originators, all other 
originators are considered to be unauthorized.

	Note 2 – The MTS abstract service specified in Rec. X.411 does not provide 
a technical realization of this element of service. Its provision may be the 
subject of further standardization.

B.78		Return of 
content	MT

	This element of service enables an originating UA to request that the 
content of a submitted message be returned with any non–delivery notifica-
tion. This will not be done, however, if any encoded information type con-
version has been performed on the message's content.

B.79		Secure 
access management	MT

	This element of service enables an MTS user to establish an associa-
tion with the MTS, or the MTS to establish an association with an MTS 
user, or an MTA to establish an association with another MTA. It also estab-
lishes the strong credentials of the objects to interact, and the context and 
security–context of the association. Secure access management can use 
either an asymmetric or a symmetric encryption technique. When access 
security is achieved through strong credentials, they can be periodically 
updated.

B.80		Sensitiv-
ity indication	IPM

	This element of service allows the originator of an IP–message to 
specify guidelines for the relative sensitivity of the message upon its receipt. 
It is the intent that the sensitivity indication should control such items as:

1)	whether the recipient should have to prove his identity to receive the 
IP–message;

2)	whether the IP–message should be allowed to be printed on a shared 
printer;

3)	whether an IPM UA should allow the recipient to forward the 
received IP–message;

4)	whether the IP–message should be allowed to be auto–forwarded.

	The sensitivity indication can be indicated to the recipient or interpreted 
directly by the recipient's IPM UA.

	If no sensitivity level is indicated, it should be assumed that the IP–message 
originator has advised no restriction on the recipient's further disposition of 
the IP–message. The recipient is free to forward, print, or otherwise do as he 
chooses with the IP–message.

	Three specific levels of sensitivity above the default are defined:

–	Personal: The IP–message is sent to the recipient as an individual, 
rather than to him in his role. There is no implication that the IP–
message is private, however.

–	Private: The IP–message contains information that should be seen 
(or heard) only by the recipient, and not by anyone else. The recip-
ient's IPM UA can provide services to enforce this intent on behalf 
of the IP–message originator.

–	Company–confidential: The IP–message contains information that 
should be treated according to company–specific procedures.

B.81		Special 
delivery	PD	PR

	This element of service allows an originating user to instruct the PDS 
to transport the letter produced form the MHS message through the ordinary 
letter mail circulation system and to deliver it by special messenger delivery.

B.82		Stored 
message alert	MS

	This element of service allows a user of an MS to register relevant sets 
of criteria that can cause an alert to be generated to the user when a message 
arrives at the MS satisfying the selected criteria. The generation of the alert 
can occur as follows:

1)	if the UA is connected and on–line to the MS, the alert message will 
be sent to the UA as soon as a message arrives at the MS that safis-
fies the registered criteria for generating alerts. If the UA is off line 
then the next time the UA connects to his MS after a message 
arrives at the MS satisfying the registered criteria, the user will be 
informed that one or more alert cases have occurred, the details of 
which can be determined by performing a Stored Message Sum-
mary;

2)	in addition to, or as an alternative to 1) above, the MS can use other 
mechanisms to inform the user.

B.83		Stored 
message auto–forward	MS

	This element of service allows a user of an MS to register requests 
that the MS auto–forward selected messages that are delivered to it. The 
user of the MS can select through registration several sets of criteria chosen 
from the attributes available in the MS, and messages meeting each set of 
criteria will be auto–forwarded to one or more users or DLs. One text per 
selection criteria can also be specified to be included with each auto–for-
warded message.

B.84		Stored 
message deletion	MS

	This element of service enables a recipient UA to delete certain of its 
messages from the MS. Messages cannot be deleted if they have not been 
previously listed.

B.85		Stored 
message fetching	MS

	This element of service enables a recipient UA to fetch from the MS a 
message, or portions of a message. The UA can fetch a message (or message 
portion) based on the same search criteria that can be used for stored mes-
sage listing.

B.86		Stored 
message listing	MS

	This element of service provides a recipient UA with a list of informa-
tion about certain of its messages stored in the MS. The information com-
prises selected attributes from a message's envelope and content and others 
added by the MS. The UA can limit the number of messages that will be 
listed.

B.87		Stored 
message summary	MS

	This element of service provides a recipient UA with a count of the 
number of messages satisfying a specified criteria based on one or more 
attributes of the message stored in the MS.

B.88		Subject 
indication	IPM

	This element of service allows the originator to indicate to the recipi-
ent(s) the subject of an IP–message being sent. The subject information is to 
be made available to the recipient.

B.89		Submis-
sion time stamp indication	MT

	This element of service enables the MTS to indicate to the originating 
UA and each recipient UA the date and time at which a message was sub-
mitted to the MTS. In the case of physical delivery, this element of service 
also enables the PDAU to indicate the date and time of submission on the 
physical message.

B.90		Typed 
body	IPM

	This element of service permits the nature and attributes of the body 
of the IP–message to be conveyed along with the body. Because the body 
can undergo conversion, the body type can change over time.

B.91		Undeliv-
erable mail with return of physical message	PD	PR

	This element of service enables the PDS to return the physical mes-
sage without delay, with reason indicated to the originator, if it cannot be 
delivered to the addressee. This is the default action to be taken by the PDS.

	Note – In the case of “poste restante” the return of the physical mes-
sage will take place after some period of time.

B.92		Use of 
distribution list	MT	PR

	This element of service enables an originating UA to specify a distri-
bution list in place of all the individual recipients (users or nested LDs) 
mentioned therein. The MTS will add the members of the list to the recipi-
ents of the message and send it to those members. Distribution lists can be 
members of distribution lists, in which case the list of recipients can be suc-
cessively expanded at several places in the MTS.

B.93		User/UA 
capabilities registration	MT

	This element of service enables a UA to indicate to its MTA, through 
registration, the unrestricted use of any or all of the following capabilities 
with respect to received messages:

1)	the content type(s) of messages it is willing to have delivered to it;

2)	the maximum content length of a message it is willing to have 
delivered to it;

3)	the encoded information type(s) of messages it is willing to have 
delivered to it.

	The MTA will not deliver to a UA a message that does not match, or 
exceeds, the capabilities registered.

ANNEX C

(to Recommendation X.400)

Elements of service modifications with respect to the 1984 version

C.1	New elements of service in 1988 (see Table C–1/X.400)

TABLE C–1/X.400



Elements of service

MT

IPM

PD

MS

Annex B 
Ref.

Additional physical rendition

X

B.2 

Basic physical rendition

X

B.7 

Content confidentiality

X

B.10

Content integrity

X

B.11

Conversion prohibition in case of 
loss of information

X

B.14

Counter collection

X

B.16

Counter collection with advice

X

B.17

Delivery via Bureaufax service

X

B.23

Designation of recipient by direc-
tory name

X

B.24

DL expansion history indication

X

B.26

DL expansion prohibited

X

B.27

EMS (express mail service)

X

B.28

Incomplete copy indication

X

B.36

Language indication

X

B.38

Latest delivery designation

X

B.39

Message flow confidentiality

X

B.40

Message origin authentication

X

B.42

Message security labelling

X

B.43

Message sequence integrity

X

B.44

Non–repudiation of delivery

X

B.49

Non–repudiation of origin

X

B.50

Non–repudiation of submission

X

B.51

Ordinary mail

X

B.53

Originator requested alternate 
recipient

X

B.56

Physical delivery notification by 
MHS

X

B.57

Physical delivery notification by 
PDS

X

B.58

Physical forwarding allowed

X

B.59

Physical forwarding prohibited

X

B.60

Probe origin authentication

X

B.64

Proof of delivery

X

B.65

Proof of submission

X

B.66

Redirection d is allowed by origi-
nator

X

B.68

Redirection of incoming messages

X

B.69

Registered mail

X

B.70

Registered mail to addressee in 
person

X

B.71

Report origin authentication

X

B.74

Request for forwarding address

X

B.75

Requested delivery method

X

B.76

Restricted delivery

X

B.77

Secure access management

X

B.79

Special delivery

X

B.81

Stored message alert

X

 B.82

Stored message auto–forward

X

 B.83

Stored message deletion

X

 B.84

Stored message fetching

X

 B.85

Stored message listing

X

 B.86

Stored message summary

X

 B.87

Undeliverable mail with return of 
physical message

X

B.91

Use of distribution list

X

B.92

User/UA capabilities registration

X

B.93

	C.2	Mapping of the 1984 and 1988 elements of service tables (see 
Figure C–1/X.400)

Figure C–1/X.400 CCITT - 0706820-89



C.3	Classification of new elements of service

	The new elements of service that were added to the 1984 X.400–
Series to create the 1988 F.400/X.400–Series Recommendations are all clas-
sified as additional optional user facilities with the following exceptions:

C.3.1	MT service

–	DL expansion history indication;

–	requested delivery method.

C.3.2	IPM service

–	DL expansion history indication;

–	language indication;

–	requested delivery method.

C.3.3	MH/PD service intercommunication

	Although some of the elements of service used in this intercommuni-
cation are classified as Base (see X.400, § 19.4), and some are classified as 
essential optional user facilities (see X.400, § 19.5), the provision of MH/
PD service intercommunication is an option itself. When this intercommuni-
cation is provided, the base elements of service and optional user facilities 
shall be supported as classified in this Recommendation.

C.3.4	Message store

	Although some of the elements of service used with the message store 
are classified as Base (see X.400, §19.6), and others are classified as essen-
tial optional user facilities (see X.400, § 19.7), the provision of a message 
store is itself an option, and therefore the classifications are applicable only 
for the provider of a message store.

C.4	Changes in classification of 1984 elements of service

	All the elements of service in 1984 have retained their 1984 classifica-
tions with the following exception:

	–	Non–receipt notification request.

C.4.1	Miscellaneous changes

	The element of service registered encoded information types in 1984 
is now called user/UA capabilities registration and it has been extended in 
functionality.

	Some of the 1984 element of service definitions have been revised 
editorially for ease of reading.

ANNEX D

(to Recommendation X.400)

Differences between CCITT Recommendation X.400
and ISO Standard 10021–1

(This Annex is not a part of this Recommendation)

	This Annex points out the major differences between this Recommendation 
and the corresponding ISO International Standard. Because the differences 
in many cases involve the inclusion or exclusion of a word, a phrase, or a 
sentence, and these occur in many places throughout the text, this Annex 
does not specifically point to these instances. Rather it summarizes the 
intent of these differences.

	The following are the major differences:

1)	The CCITT text makes references throughout to CCITT services 
and their relationship to MHS;

2)	Figure 5/X.400 showing relationships between management 
domains and corresponding notes;

3)	Roles of ADMD and PRMD in naming;

4)	Use of MHS in provision of public services (§ 17);

5)	The note about responsibility for storing deferred delivery messages 
(Annex B, § B.19) is not included in the ISO text.