From Elendor
Syntax 1: +EDIT <old text>/<new text>
Syntax 2: +EDIT<delimiter><old text><delimiter><new text>
This is like the @edit command for attributes. It takes all occurrences of
<old text> and replaces them with <new text> in your message. It then
prints out your changed message with the changes hilighted (if your
terminal supports ansi). If <old text> is a $ then <new text> is appended
to the end of your message. If <old text> is ^ then <new text> is
prepended to your message. (Warning: Sometimes the mail system has trouble
printing out your modified message with the changes hilighted. If it
doesn't look right, try using +proof to check it. +PROOF always shows the
message as it will look to others when they read it.) You can specify a
delimiter other than the "/" character by using the second syntax.
Example 1: +edit wonderful/very wonderful
(Edits all occurrences of "wonderful" in your message to "very wonderful".)
Example 2: +edit,good/bad,good/evil
(Edits all occurrences of "good/bad" to "good/evil".)