XFOR: Quoted-Printable Encoded Messages Stay in IMC

 Last reviewed: July 15, 1997
Article ID: Q146993
The information in this article applies to:
  • Microsoft Exchange Server, version 4.0

SYMPTOMS

The Microsoft Exchange Server version 4.0 Internet Mail Connector (IMC) may have problems sending outbound messages that are encoded quoted-printable. In addition, the IMC's performance will gradually degrade until it is no longer capable of delivering additional messages past the message stuck in the queue.

MORE INFORMATION

Messages sent with an attachment that have a Content-Transfer-Encoding type of quoted-printable get stuck in the outgoing IMC queue indefinitely and eventually cause the IMC to hang. In order for a message to have a content encoding type of quoted-printable, a message must be sent with an attachment that contains the proper ratio of ASCII to extended ASCII characters.

The problem occurs because IMAIL is not appending the appropriate "carriage return line feed" (CR LF) at the end of the message. The IMC appends the "dot carriage return line feed" (. CR LF) but since this isn't an appropriate end of message character string, the host keeps waiting for more data which never arrives.

All SMTP messages should always end in CRLF.CRLF. The hex representation for this ending sequence is: 

   0D 0A 2E 0D 0A
Archived IMC messages can be analyzed using a hex editor tool such as List. The hex dump below is the end of an actual message that was stuck in an IMC's outgoing queue: 

   00000110 3E 33 3E 3E 59 3E 4E 3E 34 2F 39 37 3E 3E 3E 3E
   00000120 33 3E 0D 0A 3D 31 41 2E 0D 0A
Note that the last 5 bytes of the example message above were: 

   31 41 2E 0D 0A
The first two bytes were actual message data. The last three bytes were appended to the message by the IMC as part of the ending sequence. However, the first two bytes (CRLF or 0D 0A in hex) were not appended to the end of the message by IMAIL. Thus, the ending sequence was invalid and the host didn't know that the IMC was finished sending data.

RESOLUTION

Microsoft has confirmed this to be a problem in Microsoft Exchange version 4.0. A supported fix is now available, but has not been fully regression- tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Product Support Services for more information.

Note: IMC Build 996.15 is the official hotfix that resolves this problem for Microsoft Exchange version 4.0 Servers. The files included in this hotfix are: 

   MSEXCIMC.EXE
   IMCMSG.DLL
These files are located in the following directories on the Microsoft Exchange Server: 

   MSEXCIMC.EXE:  \EXCHSRVR\CONNECT\MSEXCIMC\BIN
   IMCMSG.DLL:    \EXCHSRVR\RES

Keywords : kbbug4.00 buglist4.00
Version : 4.0
Platform : WINDOWS
Issue type : kbbug

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Last reviewed: July 15, 1997
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