http://www.rfc-editor.org/rfc/rfc5429.txt
RFC 5429: Sieve Email Filtering: Reject and Extended Reject Extensions, A. Stone2009-03-01T23:00:00-00:00The "ereject" action is intended to replace the "reject" action wherever possible. The "ereject" action is similar to "reject", but will always favor protocol-level message rejection. [STANDARDS-TRACK]