Command-line email client. More information: http://mutt.org.
mutt -f {{mailbox}}
mutt -s {{subject}} -c {{cc@example.com}} {{recipient@example.com}}
mutt -a {{file1}} {{file2}} -- {{recipient@example.com}}
mutt -i {{file}} {{recipient@example.com}}
mutt -H {{file}} {{recipient@example.com}}