Customer has SBS 2003 with Exchange 2003, and in this domain an Exchange 2010 server has been installed. All mailboxes and public folders have been migrated.
Exchange 2010 has a send connector on the hub transport to send all outbound email through a smarthost (EPA/FuseMail). Everything to now has been working
Windows updates were run on both servers last night, and since doing so, Exchange 2010 isn't sending emails out of the organisation. There are no bouncebacks (yet).
I can send mail into the organisation and to other internal users.
This is my only exposure to Exchange 2010, so I don't know what to check.