Running SBS 2008 running vitually with client computers. Outlook just decided to stop allowing emails to be sent or received externally, so still able to send message within the LAN. Internet and everything else still running so led me to believe that it was port issue. Manually checked port 25, 110 & 143 and they returned fine. Can ping out with the router. 1 thing i'm unsure about is that my server FQDN in DNS is unable to resolve. Can provide more information as neccessary. Just ask.