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Exchange Server is Dropping Attachments (Same Message Recd- User 1: winmail.dat (dropped), User 2: filename.xls (recd))

Here's the senario

Outlook 2003 SP2 / Exchange 2003 user creates an email with an excel attachment.   Addresses it to 2 people on the same remote exchange 2003 server.  The message is sent.

Two SMTP Messages are generated and sent out.

Two SMTP Messages are received by the remote SMTP Proxy Server, and forwarded on to the Exchange 2003 server.

User 1 Opens his e-mail, (Outlook 2003) and see's a message with no attachment.
User 2 Opens his e-mail, (Outlook 2003) and see's a message with the right attachment.

Looking at the SMTP Proxy Log, there are the followinig differences in the messages:

On the user who received the attachment:
 Content-Type: application/vnd.ms-excel;       name="Filename.xls" Content-Transfer-Encoding: base64 Content-Description: Filename.xls Content-Disposition: attachment;       filename="Filename.xls"

On the user who did not receive the attachment:
 Content-Type: application/ms-tnef;       name="winmail.dat" Content-Transfer-Encoding: base64

- Same Person Generated the Messages
- Same Local Exchange Server Sent the Messages
- Same Remote Exchange Server Recd the Messages
- 2 Users with same Outlook version opens the messages
- One person can see the attachment, the other person can not.  What gives?

Thanks in advance.
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1 Solution
What happens if someone else does the same test?
Preferably someone who has never sent to this user before (or create a test account specifically for this test).

Are either of these users in the active directory as mail enabled contacts?

mggiAuthor Commented:

When we type in the address manually, the e-mail w/attachment comes through fine.  (not using autocomplete)

When sending from some users personal address book, the attachment was stripped off.

Digging deeper, it appears as if a field “Sending Format” was the culprit – apparently the field was changed after some users updated their address books from their cell phones.

Got around the issue by:
   Open the users personal address book in Outlook.
   Select Contact that was not receiving attachments
   Double Click on Email address field - a form "Email Properties" should pop up.
   Make sure the field Internet Format is set to “Let Outlook decide the best sending format”
   And Click OK.

The question still remains, why cant my exchange server handle an email with a winmail.dat attachment from an exchange server?
I suspected that was the problem - which is why I wanted you to test it from another user's machine.

winmail.dat can't be handled by anything. What it means is that the attachment was munged the second it left Outlook, as the format of the message was changed. This usually happens with Mac users more than anything else.


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