DOCUMENT:Q271575  24-FEB-2001  [exchange]
TITLE   :XCON: Internet Mail Service Uses the IMCEA  Encapsulation Prefix
PRODUCT :Microsoft Exchange
PROD/VER::5.5
OPER/SYS:
KEYWORDS:exc55

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The information in this article applies to:

 - Microsoft Exchange Server, version 5.5 
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SUMMARY
=======

This article describes the IMCEA encapsulation prefix string.

MORE INFORMATION
================

The Internet Mail Service uses an IMCEA encapsulation prefix string to identify
address types other than Simple Mail Transfer Protocol (SMTP) that are sent over
the Internet Mail Service.

NOTE: The encapsulation prefix is case-sensitive, and must be uppercase to
function properly.

Some mail servers may not preserve the case of the encapsulation prefix string,
and therefore violate Request for Comment (RFC) 821, Section two (The SMTP
Model) which states:

   SMTP implementations must take care to preserve the case of user names as
   they appear in mailbox arguments.

The encapsulation prefix string is contained in a mailbox argument, as defined by
RFC 821.

If an SMTP server that is transmitting these encapsulated addresses does not
preserve the case, the Internet Mail Service does not recognize the messages as
encapsulated, and therefore generates non-delivery reports (NDRs) for them. This
behavior causes folder replication over the Internet Mail Service to fail, and
any messages for connected sites that are sent over the Internet Mail Service
are not received.

Additional query words: imceaex imc ims

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Keywords          : exc55 
Technology        : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version           : :5.5
Issue type        : kbinfo

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