heres a couple things....
You can send and receive messages up to 10 megabytes (MB) total.
As a security measure to prevent potential viruses, Gmail does not
allow you to receive executable files (such as files ending in .exe)
that could contain damaging executable code.
Gmail does not accept these types of files, even if they are sent in a
zipped (.zip, .tar, .tgz, .taz, .z, .gz) format. If someone tries to
send this type of message to your Gmail account, the message will be
bounced back to the sender.