2.3 Movement

C-c C-b

Move to the beginning of the body of the message (message-goto-body).

C-c C-i

Move to the signature of the message (message-goto-signature).

C-a

If at beginning of header value, go to beginning of line, else go to beginning of header value. (The header value comes after the header name and the colon.) This behaviour can be disabled by toggling the variable message-beginning-of-line.