I'm testing sm03 right now and I couldn't find any evidence at the moment that problems exists. Do you have a specific error message you are getting and where are you seeing the error message?
Attempted login from webmail stated something like 'unable to connect to service' and my mail client simply couldn't establish a connection at all. The problem seems to have gone away now though - all back to normal.
Please try to ping and traceroute connection to the mail server if the issue occur in the future, open a support ticket with the result attached.
