mail-indent-citation

mail-indent-citation is a compiled Lisp function in `sendmail.el'.

(mail-indent-citation)

Modify text just inserted from a message to be cited.
The inserted text should be the region.
When this function returns, the region is again around the modified text.

Normally, indent each nonblank line `mail-indentation-spaces' spaces.
However, if `mail-yank-prefix' is non-nil, insert that prefix on each line.