The major mode used in the mail buffer is Mail mode, which is much like Text mode except that various special commands are provided on the C-c prefix. These commands all have to do specifically with editing or sending the message.
mail-send).
mail-send-and-exit).
mail-to).
mail-subject).
mail-cc).
mail-bcc).
mail-fcc).
mail-text).
mail-signature).
mail-yank-original).
This command does nothing unless your command to start sending a
message was issued with Rmail.
mail-fill-yanked-message).
There are two ways to send the message. C-c C-s
(mail-send) sends the message and marks the mail buffer
unmodified, but leaves that buffer selected so that you can modify the
message (perhaps with new recipients) and send it again. C-c C-c
(mail-send-and-exit) sends and then deletes the window or
switches to another buffer. It puts the mail buffer at the lowest
priority for reselection by default, since you are finished with using
it. This is the usual way to send the message.
Mail mode provides special commands for editing the headers and text
of the message before you send it. There are five commands defined to
move point to particular header fields, all based on the prefix C-c
C-f (`C-f' is for "field"). They are C-c C-f C-t
(mail-to) to move to the `To' field, C-c C-f C-s
(mail-subject) for the `Subject' field, C-c C-f
C-c (mail-cc) for the `CC' field, C-c C-f
C-b (mail-bcc) for the `BCC' field, and C-c C-f
C-f (mail-fcc) for the `FCC' field. If the field in question
does not exist, these commands create one. We provide special motion
commands for these particular fields because they are the fields users
most often want to edit.
C-c C-t (mail-text) moves point to just after the header
separator line--that is, to the beginning of the message body text.
C-c C-w (mail-signature) adds a standard piece text at
the end of the message to say more about who you are. The text comes
from the file `.signature' in your home directory. To insert
your signature automatically, set the variable mail-signature
non-nil; then starting a mail message automatically inserts the
contents of your `.signature' file. If you want to omit your
signature from a particular message, delete it from the buffer before
you send the message.
When mail sending is invoked from the Rmail mail reader using an Rmail command, C-c C-y can be used inside the mail buffer to insert the text of the message you are replying to. Normally it indents each line of that message four spaces and eliminates most header fields. A numeric argument specifies the number of spaces to indent. An argument of just C-u says not to indent at all and not to eliminate anything. C-c C-y always uses the current message from the Rmail buffer, so you can insert several old messages by selecting one in Rmail, switching to `*mail*' and yanking it, then switching back to Rmail to select another.
You can specify the text for C-c C-y to insert at the beginning
of each line: set mail-yank-prefix to the desired string. (A
value of nil means to use indentation; this is the default.)
However, C-u C-c C-y never adds anything at the beginning of the
inserted lines, regardless of the value of mail-yank-prefix.
After using C-c C-y, you can use the command C-c C-q
(mail-fill-yanked-message) to fill the paragraphs of the yanked
old message or messages. One use of C-c C-q fills all such
paragraphs, each one individually. See section Filling Text.
You can do spelling correction on the message text you have written
with the command M-x ispell-message. If you have yanked an
incoming message into the outgoing draft, this command skips what was
yanked, but it checks the text that you yourself inserted. (It looks
for indentation or mail-yank-prefix to distinguish the cited
lines from your input.) See section Checking and Correcting Spelling.
Mail mode defines the character `%' as a word separator; this is helpful for using the word commands to edit mail addresses.
Mail mode is normally used in buffers set up automatically by the
mail command and related commands. However, you can also switch
to Mail mode in a file-visiting buffer. That is a useful thing to do if
you have saved draft message text in a file. In a file-visiting buffer,
C-c C-c does not clear the modified flag, because only saving the
file should do that. As a result, you don't get a warning about trying
to send the same message twice.
Turning on Mail mode (which C-x m does automatically) runs the
normal hooks text-mode-hook and mail-mode-hook.
Initializing a new outgoing message runs the normal hook
mail-setup-hook; if you want to add special fields to your mail
header or make other changes to the appearance of the mail buffer, use
that hook. See section Hooks.
The main difference between these hooks is just when they are
invoked. Whenever you type M-x mail, mail-mode-hook runs
as soon as the `*mail*' buffer is created. Then the
mail-setup function puts in the default contents of the buffer.
After these default contents are inserted, mail-setup-hook runs.