Yesterday, my friend asked me to send him a flash presentation which has a .exe extension. I tried mailing him using gmail attachment but wallah!!!! i got an error message which was surprising to see as gmail has their own inbuilt scanning mechanism.
The simplest solution to this problem is to remove the extension of file and then attache the file. For eg. suppose you want to attache abc.exe, rename the file and remove the .exe part so the file will now become abc simply. You can also try changing the extension of file to more acceptable file formats like .txt, .doc etc.
You can do the same for attaching batch files(.bat) as well.