# mail > The command operates on the user's mailbox if no argument is given. > To send an email the message body is built from standard input. - Send a typed email message. The commandline below continues after pressing Enter key. Input CC email-id (optional) press Enter key. Input message text (can be multi-line). Press "Ctrl-D" key to complete the message text: `mail --subject={{"subject line"}} {{to_user@example.com}}` - Send an email that contains file content: `mail --subject={{"$HOSTNAME filename.txt"}} {{to_user@example.com}} < {{path/to/filename.txt}}` - Send a tar.gz file as an attachment: `tar cvzf - {{path/to/directory1 path/to/directory2}} | uuencode {{data.tar.gz}} | mail --subject={{"subject line"}} {{to_user@example.com}}`