We have a client who use exchange 2010 on an SBS2011 box. they cant receive any external emails, internally its fine, and they can send externally. they use Trend Worry Free Business for spam filtering which sits on the SBS server. i have disabled Trend this and still the same result. when i perform a message trace, it shows no external emails even hitting the server.
i have attached a bounce back for you to see.
any help will be appreciated.