Mailing Lists

If I send a message to a mail relay destined for my mail store (on a different host), where does the directory lookup take place? On the mail relay, or at the mail store? Similarly, if I send a message to a static disribution list, where does it blow up all the addresses and do a lookup? In addition, are these lookups done through the cache from dirsync, or does it go to the directory server? Does a dynamic mailing list behave the same way, or does it need to go to the directory server to build the list? Any clarity would be much appreciated. Thanks!!

I am running IMS 5.1 on each host.

[620 byte] By [705739] at [2007-11-25 8:37:42]