Expirysource, noexpirysource Channel Options

Header-based message expiration
(New in Messaging Server 7.0.) The  channel option instructs the MTA to honor Expiry-date: header fields - messages will be returned as undeliverable if the time specified by this header field is exceeded. disables this check and is the default.

See also:
 * Headers channel options
 * Processing control and job submission channel options
 * Channel options