Email attachements sent using Outlook (all flavours) via Exchange 2007 - are being stripped down to 1kb and are unreadable when sent to external clients.

We have this week migrated servers to 2007 from 2003.  This has pretty much gone smoothly - however an interesting problem has arisen.  When PDFs and JPEGs and other file attachements are sent from Outlook clients to external clients they are stripped down to 1kb and are unreadable by those external clients.  Internal client receive the full document no problem.  I cannot work ou when the problem is.  No limits have been set up as far a I can see - in terms of file size.  An mailbox limits are no where near at capacity.  Bit lost hope some one has an idea of what is causing this!
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SembeeConnect With a Mentor Commented:
I would blame the Symantec application. If I find Symantec software on the server it is the usual cause of any problems and should be removed to confirm that is the case. It is not Exchange doing the attachment removal.

If there is Symantec file level AV on the machine as well then that should be removed.

Disabling the AV is not enough, as it still has its hooks in the system.

Check which options are selected in Message Formats. Check the MIME formats.

What is the type of attachment that appear for external recepients?

Did you run the Update Rollup 5 after migration? - 
Exchange wouldn't do that on its own. Something else is doing it.
Anything else installed on the machine? AV, Antispam etc? Do outbound email go out through another service/server?

If it was limits then the message would be blocked, not stripped, as Exchange looks at the entire message for the limit.

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JoseCopoviAuthor Commented:
Hi guys.  Outbound email is sent out via SMTP directly from  a second SMTP sender directly from the server.  As for AV we have  got Symantec Mail Security on the system.  The attachements show as for example PDF but severely reduced in file size.  The strange thing is that the gif image that is used in theie email signatures is sent intact.  
JoseCopoviAuthor Commented:
Just to update this if i zip the files they go through intact.  Unzipped are replaced with placeholders at 0kb
upul007Connect With a Mentor Commented:
Check the Symantec Virus Guard rules/filters to see if there is any option that may cause this issue. Perhaps Symantec Support may need to be contacted regarding this in order to find a work around.
JoseCopoviAuthor Commented:
OK I am going to to remove the Symantec applications, will let you know
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