There are several commands allowing you to quit the compose mode.
Typing the end-of-file character (C-D) on a line alone finishes
compose mode and sends the message to its destination. The C-D
character looses its special meaning if ignoreeof
mail variable
is set.
If mail variable dot
is set, typing dot (.) on a line
alone achieves the same effect as C-D above.
Finally, using ~. escape always quits compose mode and sends out the composed message.
To abort composing of a message without sending it, type interrupt
character (by default, C-C) twice. This behavior is disabled
when mail variable ignore
is set. In this case, you can use
~x escape to achieve the same effect.