After the latest updates were pushed to my SBS 2011 server, all outbound email is delayed and eventually fails to be delivered. Inbound mail works fine. The last time I successfully sent outbound mail was September 22. Microsoft pushed patches out after
that date and since then I can't send out mail. At first I thought it was to just a couple of domains but I recently learned all domains fail delivery from all my users.
I went to MXtoolbox and ran the tests there and all seems well, my domain is not blacklisted and everything else seems to be correct. I am not an Exchange expert and at this point I don't have a clue what to do next.
My server is fully patched with all the patches Microsoft Update/WSUS recommends or pushes out.