Deferredsource, nodeferredsourcedeferreddestinction, nodeferreddestination Channel Options

From MsgServerDocWiki

Deferred delivery dates (deferreddestination, nodeferreddestination)

The deferredsource and deferreddestination channel option implement recognition and honoring of the Deferred-delivery: header. These options are newly implemented in the 7.0 release of Messaging Server. When set on a source or destination channel respectively, messages with a deferred delivery date in the future will be held in that channel queue until the deferred delivery date is reached. See RFC 2156 for details on the format and operation of the Deferred-delivery: header. Both channel options accept a single integer argument specifying the maximum number of seconds in the future a Deferred-delivery: date value can specify and still be honored. If both options apply to a transaction the lower of the two limits will apply. The integer arguments are optional in a traditional imta.cnf file - if the value is omitted a default of 60*60*24*7 (7 days) will be assumed.

Prior to the 7.0 release the deferred provides similar functionality to deferreddestination. In 7.0 the MTA accepts deferred as a synonym for deferreddestination in the imta.cnf file. Note also that prior to 7.0 deferred delivery was not a reliable service. In particular, deferred handling information does not survive job controller restarts.

nodeferredsourceand nodeferreddestination are the defaults. It is important to realize that while support for deferred message processing is mandated by RFC 2156, actual implemention of it effectively lets people use the mail system as an extension of their disk quota.