17.2 Mail

     Using the same example, if you have mail for both 1:135/142 and
     26:1305/142, all mail (for both addresses) would be delivered
     during the same session. This is true for both inbound and
     outbound connections.

     If you know that a system is EMSI capable and you have regular
     mail traffic with more than one of its AKAs, you can HOLD mail
     for the system's other AKAs and only allow the Mailer (FD) to
     call one of the addresses. When the session is established, all
     of the remote system's AKAs are processed.

     This probably sounds more confusing than it really is. So to make
     a long story short, make sure you have the "Present all AKAs to
     remote" option enabled (Mailer>Miscellaneous) and play it by ear.