We recently have been experiencing many issues with newer users on our exchange server. Both internal and external users are getting 550 5.1.1 RESOLVER.ADR.RecipNotFound; not found bounce backs when trying to email these users. However it doesn't seem to be every email that gets the NDR. The only change to our network as of recent was adding a domain trust between us and another network(which uses Lotus Notes). Any ideas why only these new users are having problems?
Our enviroment is made up of 2 ADS Servers running on Windows 2003 Standard SP2 and a 3 Servers all internal running in a Cas/Hub/MB format. All incoming mail is filtered through a Sonicwall spam filter. However the kickbacks come from both internal and external email so we have ruled that out.
Any thoughts?
