I wanted to email my tax data to my accountant. So, I made a self-extracting PGP archive several megabytes in size. Gmail wouldn't let me send it until I tacked on .remove after the .exe extension.
It's not really an unreasonable thing, IMO. Google is just making sure the file won't run semi-automatically upon being downloaded. Ending in a random extension prevents that, since the user has to deliberately rename the file first.
IIRC, you can also just strip the file extension altogether.
I had to send some DLLs once -- that was a pain. I think the only thing that ended up working was zipping them and stripping the .zip extension off the file.
Once I wanted to send a zip file of malicious php files. Google (correctly) identified them as harmful. It wouldn't allow me to send them even though I tried to pack them into zip, tar.gz and tar.bz2 files. In the end I wrote a script that rot13 encoded the files and was able to send the files.
