In VPOP3, Mappings are a way of explicitly linking an email address to a user or list. They can also be used to indicate that an email address is remote, even though it would otherwise appear to be a local email address.
In other email servers, a similar feature may be called 'aliases'
In VPOP3, by default, a user (or list) will have implied Mappings of <username>@<domains> → <username> . For an explanation of the <domains> value, see the Domains to use section of this article.
The implied Mappings only apply if there are no other Mappings which have matched the address previously.
You can turn off the implied Mappings, either in the Local Mail -> General settings - the “Disable default user→ user mappings for local/incoming SMTP mail” option, or in the appropriate Mail Collector (POP3 Routing → Configure Routing Options, the “Disable default user → user mappings” option).
For implied Mappings or Mappings without an explicit email domain set, VPOP3 uses a list of domains set elsewhere for checking the mappings.
The <domains> list will depend on how the message is arriving at VPOP3.
For email which arrives at VPOP3 using SMTP, then the <domains> list is any domain listed in the Local Domains setting.
Each Mapping has 5 settings
The email address setting tells VPOP3 which email address to look for when searching mappings.
You can specify the email address as:
You can use * and ? wildcards in the mappings, eg you could map
*@mydomain.com → me, or
email@example.com → albert
Note that, while you can use wildcards in the domain part of the email address, this should be used with care. For instance, if you have a mapping of
bill@* → bill, then if a message is CC'd to firstname.lastname@example.org, it will still be sent to your 'bill' user, even though that is probably not what was intended. Using wildcards in the domain part should probably be limited to using them if you have subdomains for divisions - eg
sales@*.ourcompany.com → sales would work if you wanted messages for email@example.com and firstname.lastname@example.org both to go to the 'sales' user/list.
If several Mappings match an email address, then all of them will be processed (except for ~@ Mappings)
The Target is where any messages which match the Email Address part will be sent. You can choose any user/list from here.
The *REMOTE target is a special case. This tells VPOP3 that the specified Email Address is a valid email address, but is not handled by this VPOP3 server. This can be useful if you have some users in your domain which are handled by another server.
For instance if you have a user email@example.com who collects his mail directly from a separate account at your ISP, you can create a Mapping of
mike → *REMOTE.
What then is configured, then if a local user sends a message to firstname.lastname@example.org, rather than VPOP3 complaining that the 'mike' user doesn't exist, VPOP3 will put the message into the out queue to be sent to the Internet. Similarly, if a message comes in addressed to email@example.com, VPOP3 will simply ignore it (assuming that it has also been copied, by the ISP, to the relevant mailbox elsewhere).
See How to tell VPOP3 some users in the local domain are not to be handled by VPOP3 for more details.
The Type setting lets you limit when the Mapping applies. You can choose:
If the Type is set to POP3, then this tells VPOP3 which Mail Collectors the Mapping will apply to, you can choose either 'All In Mail Settings' or a specific Mail Collector
This allows you to set your own comments against the Mapping, for future reference