Usage: send-hook
[!]pattern command
This command can be used to execute arbitrary configuration commands based upon recipients of the message. pattern is a regular expression matching the desired address. command is executed when regexp matches recipients of the message. When multiple matches occur, commands are executed in the order they are specified in the muttrc.
See matching messages for information on the exact format of pattern.
Example: send-hook mutt "set mime_forward signature=''"
Another typical use for this command is to change the values of the $attribution, $signature and $locale variables in order to change the language of the attributions and signatures based upon the recipients.
Note: the send-hook's are only executed ONCE after getting the initial list of recipients. Adding a recipient after replying or editing the message will NOT cause any send-hook to be executed.