Some workplaces have tight restrictions on email attachments containing binaries. So, people in such environments request me to send the attachment by zipping up the suspicious files and encrypting it. Zip has had support for password protection for a long time so most receivers will be able to unzip the contents if you can provide the password you used for encrypting.
To create the zip files:
$ zip --password mypassword foobar.zip files to zip go here
Note that zip uses weak encryption. Use it only to get around the email servers, not for actually hiding data.
Tried with: Ubuntu 14.04