Recently I needed to send a script to one of my co-workers from the server. One way to do that is copy the script using scp to my PC and send it as usual. But there is a more efficient way to do that with mutt:
$ mutt -s "Subject" -a /tmp/file.tar.gz firstname.lastname@example.org < /tmp/message-body.txt
I hope that all parameters are understandable. So, having mutt and using that command you can easily send email with attached file from command line.