DKIM MTA options

New in Messaging Server 7.0.5 are several MTA and channel options that affect message handing based on the presence of certain DKIM signatures. See also the  and   channel options, which perform a similar function on a per-channel basis.

See also:
 * dkim_ignore_domains MTA Option
 * dkim_preserve_domains MTA Option
 * dkim_remove_domains MTA Option
 * dkimignore Option
 * destinationdkimignore Option
 * DKIM channel options
 * MTA options