When upgrading your Exchange server to 2010, here is a list of things you should review before moving forward:
1. Clean up old mailboxes: Backup and remove old/Stale mailboxes from exchange 2003 system
2. Clean up mailboxes: Remove deleted items, Purge junk mail folders
3. Identify any archive PST files that users may have on their local systems and move and label them to a central location on the server if they wish for them to be imported into the existing system
4. Identify All domains to be accepted by the mail server
5. Identify need for Active sync. Active sync policies need to be identified and new policies need to be distributed to end users.
6. Mailbox quotas need to be identified
7. Identify retention policies
8. Identify need for any devices that need to relay email to the mail server
9. Spam Rules need to be identified
10. Verify all clients are using outlook 2003 or greater
11. Best practices needs to be run against the server and any issues identified and resolved.
12. Identify certificate information. Unified communications certificate needs to be purchased based on machine name, public name of server, Normal certificate will hold 5 FQDN names unless the internal domain is the same as the external domain.
13. New 2008 x64 server needs be spun up in virtual environment partitioned off so that information store and log files can be stored on their own server.
14. Exchange needs to be installed and configured on server
15. Smart hosts need to be configured if used
16. Configure retention policy
17. Configured email policy
18. Configure any relay’s needed on the network
19. Database and log files need to be moved to appropriate locations on the server
20. Firewall rules need to be implemented to allow port 25 traffic to the server or another port if so indicated in requirements.
21. Connector needs to be built to communicate between the 2003 and 2010 exchange servers
22. Test of migration of one mailbox and verify mail flow between the servers and the outside
23. Schedule move of mailboxes to new server
24. Import PSTs as needed
25. Configure Relays for devices
26. Public folder replication needs be setup and moved to the new server
27. Complete testing
28. Setup external url information in 2003 access to web is via https://FQDN/exchange and in 2010 it is https://FQDn/owa if the client would like to keep /exchange a redirect needs to be configured.
29. Anti virus needs be setup on the exchange server
30. Backups of the server need to be configured, tested and verified
31. Test of active sync and active sync rules
32. Test of all secure certificates
33. Verify all clients connect smoothly to the new server using Auto Discover.