I've looked around EE for this issue and haven't found the answer I need yet.
I have a website that sends PDFs as an email attachment. I get the PDF fine and it's named as it should be. Two of my users have Outlook 2003 (on XP SP2) and their attachments are renamed to "ATT12323.dat" (the numbers change...)
I found a suggestion that the file was too big. It's only 60 KB.
I found a suggestion that the filename was too long. It's only 12 characters.
People suggested sending in text mode, which I am.
Again, I and other users get the email just fine, it's Outlook that's renaming it for some reason.
The user's receive other PDFs, so I'm a little baffled as to why it's happening for some and not others.