XCON: Client Cannot Retrieve Message in Parts Using SSL

ID: Q194998

The information in this article applies to:

Microsoft Exchange Server, version 5.5

SYMPTOMS

IMAP4 customers using Netscape Messenger 4.5 enabled for Secure Socket Layer (SSL) against an Exchange Server 5.5 IMAP4rev1 computer, might encounter message content loss. Messages 6 KB in size or greater might be truncated (this is regardless if messages contain attachments or not).

CAUSE

Netscape Messenger 4.5 has moved to fetching messages in chunks (prior releases of Messenger always fetched the entire message). The command Messenger now issues to fetch a message is as follows:


   11 UID fetch 320 (UID RFC822.SIZE BODY[]&lt;0.6144&gt;)

When using clear text, the server will respond to the above command with exactly 6144 bytes of message data. When using SSL, Exchange Server can return more than 6144 bytes of message data. When more bytes than requested is received by Messenger, the client logs out without retrieving any more message data. Hence, the message is displayed truncated.

RESOLUTION

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For more information, please see the following article in the Microsoft Knowledge Base:

Q191014 XGEN: How to Obtain the Latest Exchange Server 5.5 Service Pack

The English version of this fix should have the following file attributes or later:

Component: Information Store


   File Name    Version
   -----------------------
   Gapi32.dll   5.5.2437.0
   Mdbmsg.dll   5.5.2437.0
   Netif.dll    5.5.2437.0
   Store.exe    5.5.2437.0

WORKAROUND

The obvious work around is to turn off SSL with Netscape 4.5. For customers who need to continue using SSL with Netscape Messenger 4.5, a client configuration change can be made which will alleviate the problem.

When added to the Netscape user Pref.js file, the following line will turn off fetching in chunks:


   user_pref("mail.imap.fetch_by_chunks", false);

Netscape Messenger 4.5 will return to fetching the entire message in one command (as was the behavior in Netscape Messenger 4.07). Upon restarting the client, messages that were previously truncated can be fetched again and all message content displayed.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. We are currently working on a fix to correct this problem.

Keywords : exc55sp2fix
Version : WinNT:5.5
Platform : winnt
Issue type : kbbug