XCON: Internet Mail Service Uses the IMCEA Encapsulation Prefix String (271575)


The information in this article applies to:

  • Microsoft Exchange Server 5.5
This article was previously published under Q271575

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.
Modification Type:MinorLast Reviewed:4/25/2005
Keywords:kbinfo KB271575
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