Mtpriority policy MTA option

Message Transfer Priority Policy: (string)
New in 8.0. The  MTA option is used to specify a policy name for the handling of message transfer priorities the MTA has been  configured to support. This name is announced in the SMTP EHLO response on any channel where the MT-PRIORITY extension is enabled. The default is that this option is not set, which means that no policy is announced.

Note that the MTA&#x27;s Priority Assignment Policy is as follows: MT-PRIORITY values of -9,..,-4 are mapped to "non-urgent" priority; MT-PRIORITY values of -3,..,3 are mapped to "normal" priority; MT-PRIORITY values of 4,..,9 are mapped to "urgent" priority. An explicit MT-PRIORITY value specified on a submitted message will override the MTA&#x27;s older priority (e.g., Priority: header line based) handling, as well as any of the MTA&#x27;s older size-based priority override adjustments (e.g.,, etc.). (However, a Sieve filter  action can override even an explicit MT-PRIORITY value.) Messages that come in without an explicitly specified MT-PRIORITY are subject to the MTA&#x27;s older priority handling, and for MT-PRIORITY purposes (such as mapping table probes including MT-PRIORITY value) will be considered to have an MT-PRIORITY value of 0.

Note that the MTA&#x27;s Priority Assignment Policy, described above, is essentially that of the "MIXER" Priority Assignment Policy defined in Appendix B of RFC 6710 -- this is a natural mapping for the MTA as its older Priority: header support was similarly based on RFC 2156 (MIXER: Mapping between X.400 and RFC 822/MIME).

See also:
 * mtprioritiesallowed Option
 * non_urgent_block_limit MTA Option
 * nonurgentblocklimit Option
 * Job Controller priority-based processing