We are going to migrate our SBS2003 server from downloading e-mail via the POP3 connector to getting e-mail sent directly to the server via SMTP. The static IP address is already setup and working. Following is the procedure I've come up with. Did I miss anything, or have anything unnecessary?
• Preliminary Setup (several days before we start all of this)
○ Change TTL on MX DNS record to something short (like 15 or 30 minutes).
○ Forward port 25 to the server (Cisco router configuration).
○ Make sure everything still works.
• Switch outgoing mail to not go through Godaddy anymore.
○ Run E-mail and Internet Connection Wizard on server.
§ Change it to "Use DNS to route e-mail".
○ Make sure outgoing SMTP works.
§ Make sure we aren't running an open relay (spammers could send e-mail via our e-mail server): DNSGoodies
• Switch incoming mail to not go through Godaddy anymore.
○ Run E-mail and Internet Connection Wizard on server.
§ Check the box "Use Exchange" (both boxes will be checked, so we are getting e-mail both directly via our server and via Godaddy.
○ If we can test receiving e-mail without switching the MX DNS record to the new address, do it now.
§ Could possibly be done by setting up a subdomain's MX record to point to our server.
§ Could possibly be done by sending e-mail to test@IPAddressHere.
□ Could not get this to work with a different Exchange server already setup for SMTP.
○ Switch the MX DNS record to point to MyIPAddress.
○ E-mail should switch over within 30 minutes, may take up to 48 hours (depends on TTL of MX record).
○ Test receiving e-mail on at least one account.
§ POP3 Connector should be disabled for that account to eliminate chance of the mail going through Godaddy while we think it's coming straight to our server.
§ Don't need to disable it for all accounts
○ Make sure our server doesn't cause backscatter
• Post Setup (several days after everything is working)
○ Change MX DNS record to something longer than 15 or 30 minutes.
○ Run E-mail and Internet Connection Wizard on server.
§ Uncheck the box to use the POP3 Connector.
○ Make sure that e-mail is still working.
○ Keep a watch on Spamhaus to make sure we don't end up on a list of known spammers.
○ Setup anti-spam filter based on this.
§ Instructions