You may have noticed that GMail blocks sending any email that contains a "EXE, OCX, COM, BAT or DLL" attachments. 

In fact, GMail  blocks the attachment EVEN if you put the file inside a ZIP file (encrypted or otherwise).

Workaround

In order to send EXEs, just rename them to EXE.REMOVEME (or something fancy).  For e.g. if you are sending XYZ.EXE, rename it to XYZ.EXE.REMOVEME.  You can now send this attachment via GMail.

Attaching multiple files

If you have multiple EXEs, DLLs, etc, put these inside a zip file and rename the ZIP  file as above.