By employing local SMTP, the burden of routing messages to suitable storage becomes a configuration problem within the mail system itself.
Here, imip-agent connects to the mail transport agent (MTA) and sends a message to an explicitly-indicated local user. For example:
With such a local user indicated, the message is then routed to a mail delivery mechanism, perhaps by converting the local address to a local system user identity (a user with an account on the system running the software). For example:
The local delivery mechanism would then deposit the message in the user's mailbox. MTAs typically provide such routing for local system users by default.
Alternatively, with a local user having been indicated, a message would be routed for delivery by a mail storage solution which would accept the message for the indicated user and deliver it to that user's mailbox. For example:
Where such routing is performed to mailbox providers employing LMTP, some additional configuration effort may be required. See the mailbox integration guide for more details.
Some of the routing for explicitly-indicated local users is dependent on the identification of users and is described in the LDAP and simple integration guides.