filenames getting mangled

[Chris Yuzik]

A strange problem was reported to me today.

Email attachments from one of our people is fine as long as it stays 
within our server, but if he emails it externally, the attachment goes 
but the filename gets mangled. I've had him send me a copy of the PDF 
file via email and cc my gmail account, and I get the file fine with my 
regular email, but when it arrives to gmail, the filename and extension 
are buggered; if I save the file and rename it to "test.pdf" it's fine. 
The odd thing is that the attachment I receive internally apparently has 
a different name than it did on his computer.

I've tried emailing the same attachment to my gmail account from Outlook 
2007 and from Thunderbird, and it always arrives as expected.

Anyone seen this before or have any ideas?