Defer_group_processing MTA option

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Mailing list controls (defer_group_processing)

The defer_group_processing MTA option sets a default for whether direct LDAP group (list) expansion is performed "in-line", or whether it is deferred (performed via the reprocess channel). The default is 1 (true); that is, by default group expansion is deferred to the reprocess channel.

Note that when an address is deferred, the usual incoming recipient access mapping table (specifically, ORIG_SEND_ACCESS, SEND_ACCESS, ORIG_MAIL_ACCESS, and MAIL_ACCESS) checks are not performed; such checks don't take place until the reprocess channel runs and expands the address. Also, the originator address checking (via attributes such as mgrpAllowedBroadcaster, etc.) is deferred. (If the [dis]allowed broadcasters are a large dynamic group themselves, deferring this expansion is very desirable so that that lookup doesn't slow down the SMTP dialogue.) The reprocess channel when it runs will then perform all the normal access checks as if it were the original channel. In particular, the original transport and application fields (used in ORIG_MAIL_ACCESS and MAIL_ACCESS mapping tables) are available to the reprocess channel, and hence checks such as dns_verify callouts can still be performed at this later time.

If defer_group_processing=0 is set, so that the default is that groups are expanded "in-line" (for instance, during an SMTP dialogue), then deferred expansion may still be set for particular groups either by setting the mailDeferProcessing attribute (or more precisely whatever attribute is named by the ldap_reprocess MTA option) to Yes, or (deprecated) by setting the (multi-valued) mailDeliveryOption attribute (or more precisely, whatever attribute is named by the ldap_delivery_option MTA option) to have a value members_offline.

See also: MTA options, Option value syntax, Getting option changes to take effect, MTA options, listed alphabetically, MTA options, listed by functional groups, Mailings lists and groups, Mailing list options, LDAP and URL lookup general options, Direct LDAP alias and address reversal lookup options.