I found a this great analogy on how MSMQ works

URL : Full MEssage

"MSMQ works similar to how USPS works.

You write your letter, write in address (queue format name), attach stamp and put it into your mail box with raised red flag (send the message using MSMQ).

Your mail (message) then sits in this mail box near your house (outgoing queue). Note at that point you can get address wrong on your letter (bad format name), however that won’t stop you from putting letter into mail box (sending it).

OK, so later one mail man comes (network connection is established). Mail man picks your mail (MSMQ connects to the destination server) and if everything is OK it goes through the system (network) and ends up in receiving mail box (destination queue). Recipient (your application on the server) don’t have to be near (don’t have to be running) this mail box (queue) for mail to arrive.

At some point somebody (your application) opens mail box (application on the server reads from the destination queue) and gets mail.

What could go wrong here? Well, you can get address wrong. Mail man can never come (no network connection on device). Destination might be inaccessible, say avalanche blocked the roads (server is down or no network path to it) or there’s civil disturbance and it’s blocked out by the police (firewall or security configuration prevents connection to the server).

Another thing: I’m not absolutely sure, but you might have to install web server and configure MSMQ ISAPI DLL for SRMP to work."