The SMTP server receives mail files from TCP clients or the JES spool, and forwards mail files to other SMTP servers or to the JES spool. User identities and mail security labels are not processed.
You must run a separate instance of SMTP for each security label you need to support. Run each one under a different job name assigned to a user ID with the appropriate security label. You can run multiple SMTP servers on the same unrestricted stack. Define a VIPA in a network security zone with the appropriate security label for each server on that stack. Use the PORT reservation statement in the TCPIP profile or the LISTENONADDRESS keyword in the SMTP configuration file to override the bind address of each job to the appropriate VIPA. You can also run multiple SMTP servers with one server per restricted stack using stack affinity. In this case, it is not necessary to override the INADDR_ANY bind address.
Spool files routed to an instance of SMTP must have an equivalent security label.
Spool files created by SMTP carry the SMTP security label. SMTP servers are permitted to connect only to other SMTP servers with an equivalent security label.