Alias domains MTA option

Domains in alias lookups
The  MTA option takes a bit encoded integer  argument controlling the format of  alias file (and hence in Unified Configuration alias option)  and alias database lookups. (This option does not affect   lookups.)

As of Messaging Server 7.0-3.01, the default value of   is 6, meaning that alias file and  alias database lookups probe first with the entire address, then probe with a wildcarded localpart plus domain, and finally addresses matching the local channel probe with solely the localpart; previously, the default value had been ,  meaning that alias file and alias database lookups would probe with only the localpart (mailbox portion) of the address. Note that for addresses matching the local channel, the a localpart-only probe is made even if bit 0 (value 1) is not set. Setting bit 1 (value 2) causes a probe to be made using the entire address (including the domain name). Setting bit 2 (value 4) when bit 1 (value 2) is also set causes an additional, fall-through wildcard  probe  -- effectively a "domain catchall address" probe -- to be made. Indeed, if the address included a subaddress, setting bit 2 (value 4) causes two wildcard  probes to be made, first      and then   . (For wildcarding solely the subaddress, not the localpart, see the  channel option.)  If all bits are set, i.e., , then the order of the probes is to first probe with the entire address (the most specific check), next probe with a wildcard   localpart plus the domain name, and finally probe with just the localpart.

Bit 0 is the least significant bit.

Note that by default only addresses rewritten to the local channel are checked against the alias file and  alias database. However, via use of the   channel option, it is possible to cause addresses matching other channels to be checked against the alias file and alias database for aliases, at which point   can affect aliasing of addresses rewriting to those other channels. Note that the effect of bit 2 (value 4), that is, the probes with the  character as the localpart, can be controlled on a per-channel basis via the   channel option.

See also:
 * Alias and address MTA options
 * aliaslocal Option
 * aliaswild Option
 * Alias file format
 * Alias database
 * Local channel
 * subaddresswild Option
 * alias_url0 MTA Option
 * Alias options