Even though your Exchange Server 2003 has Service Pack 1, which supports domain rename in a Windows Server 2003 Active Directory forest, when you run Rendom.exe to change the DNS or NetBIOS domain name, your receive:
Found Exchange Server in the forest. Domain rename is supported only if Exchange Server version is Exchange 2003 SP1 and above.
This problem occurs because the SP1 update failed to change the Exchange Server 2003 versionNumber attribute to 7226 on the Policy name object in Active Directory.
To fix this problem:
1. Start / Run / adsiedit.msc / OK.
2. Expand CN=Configuration / CN=Services / CN=Microsoft Exchange.
3. Right-click CN=policy name and press Properties.
4. Double-click the versionNumber attribute.
5. In the Integer Attribute Editor, change the data value to 7226.
6. Press OK and OK.