To send an e-mail message in Emacs, type C-x m. This selects and initializes a buffer named ‘*mail*’, where you can edit the text and headers of the message. Finally, type C-c C-s or C-c C-c to send the message.
The command C-x 4 m (
compose-mail-other-window) does the
same as C-x m, except it displays the mail buffer in a different
window. The command C-x 5 m (
creates a new frame for the mail buffer.
Because the mail buffer is an ordinary Emacs buffer, you can switch to other buffers while in the middle of composing mail, and switch back later (or never). If you type C-x m again when you have been composing another message but have not sent it, Emacs asks for confirmation before erasing the old message. If you answer n, Emacs selects the mail buffer with its old contents, so you can finish the old message and send it. C-u C-x m is another way to do this. Sending the message marks the mail buffer “unmodified,” which avoids the need for confirmation when C-x m is next used.
If you want to send another message before finishing the current message, use the command M-x rename-uniquely to rename the current mail buffer (see Misc Buffer). Then you can use C-x m to make a new mail buffer, and work with each mail buffer independently.
Before using Emacs to send mail, you may need to customize the
send-mail-function if your system is not set up to
deliver mail directly via SMTP (see Mail Sending). In addition,
you may need to customize
user-mail-address if the system
cannot receive mail via SMTP (see Mail Headers).