Software

this is an anna777 question, but here is what i guess happens. exchange tries to deliver for some (configured) amount of time, like 3 days...then it dumps it into dead letter mailbox. look in there, see if you don't see your non-deliverable mail. you should be able to configure how it behaves in there, in my domino server it stays in for 3 more days, then purges out (i think...i am going to have to go check now!)...hope this helps...

This is an empty distribution list. Anything sent to one of the SMTP addresses of this DL never makes it to a queue, therefore no NDR is generated and nothing is dumped in dead letter box. But where does it go?

I found this question interesting, so after some reading and a few tests, this is what I've been able to come up with:

The message comes in via the Internet Mail Service and transfers to the MTA. The MTA then attempts to deliver to the Information Store. The IS has no storage for the address, so it sends the message back. The message bounces back and forth until it is seen as a mail loop. On the server I tested, the message went back and forth 8 times before it "gave up". This took less thana minute. The system then generates a couple of events -- a 12071 and 4098. The 12071 event refers to an archive filename, but apparently the file is not archived, it is deleted, as no file with this name exists anymore on my system. You should see these events on your server, too, and can take a look at message tracking in the MTA, IS and IMS to reconstruct this as well.

This isn't terribly detailed as to how the message gets passed between the various queues (BTW, all messages pass throughqueues if only instantaneously) but it gives a rough idea. If you need even more detail, lots of reading is available on TechNet re: MTA routing and Exchange architecture.

HTH...