Systemfilter MTA option

The  MTA option takes a Sieve filter as its value, referred to as the MTA system Sieve filter. (In legacy configuration, this Sieve was stored in the   file.) Normally, this Sieve filter will  be applied to every message processed by the MTA, at every enqueue; but see the    and   channel options which can disable application of selected Sieve filters on a per-channel basis.

Because the MTA system Sieve filter, like channel filters, is controlled by the MTA administrator rather than by users, certain Sieve features are available to it not normally available to users.

Note that because the MTA system Sieve filter is applied so frequently (normally to every message, at every enqueue), it is particularly important that it be a well-written, efficient Sieve filter.

Note that a summary of the Sieve actions performed upon a message, whether from  the   MTA system Sieve filter or any other Sieve applying to a message, may be recorded in the MTA message transaction log file by enabling the   MTA option. This is truly a summary of what was performed; it will not show actions that were superceded or considered but not performed.

Since the MTA system filter typically consists of more than one line of text, its value cannot be easily set using the msconfig set command. The  command can be used  for manual editing of the system filter and the recipe language   function should be used for automating filter updates.

See also:
 * Sieve language
 * Sieve filters
 * Sieve supported extensions
 * Brief overview of Sieve language elements
 * destinationfilter Option
 * sourcefilter Option
 * disabledestinationfilter Option
 * disablesourcefilter Option
 * Sieve filter MTA options
 * log_filter MTA Option