reject <reason : string> ;
The "reject" action refuses delivery of a message by sending back a notification to the sender. It resends the message to the sender, wrapping it in a "reject" form, noting that it was rejected by the recipient.
In the following script, rejects any matching messages and returns it to the sender.
if header :contains "from" "coyote@desert.example.org" {
reject "I am not taking mail from you, and I don't want
your birdseed, either!";
}
Core - require "reject"; statement suggested
RFC3028