The email server will probably be offline for brief periods of time Saturday and Sunday (5 Dec and 6 Dec) while the final migration to the new hardware is completed.The outages should not be over 15 minutes, and it is quite possible that there will be no outage at all. However, since part of the changes will involve updating the DNS settings, you might be unable to reach the mail server until the DNS changes propagate out to your DNS. You should be able to access the webmail during this time if necessary. Also, if you know how to change your DNS server you can always point to 75.148.117.92 as the main DNS for fastest possible propagation.