Question : exchange MTA,  all sent mail is NDR'd

A non-delivery report with a status code of 5.3.0 was generated for recipient rfc822;[email protected].tw (Message-ID  <[email protected]m>).  
Causes: Exchange mistakenly attempted mail delivery to an incorrect MTA route.  
For more information, click http://www.microsoft.com/contentredirect.asp.    
Solution: Check your route and topology; use the winroute tool to ensure the routes are properly replicated between servers and routing groups.

The server was running fine for more than half a year now, and all of a sudden.... we are experiencing this.. i have seen accepted answers for this exact problem but the resources are no longer on this site....

Thanks for any help i get...

cw

Answer : exchange MTA,  all sent mail is NDR'd

You should restart SMTP Service after any changes you make in the SMTP Virtual server.