Communications Suite: Confirming That Upgrade Procedure from 5.2
re: upgrading directly from iPlanet Messaging Server 5.2 to Communications Suite 5 (that is, Messaging Server 6.3), the Sun Java Communications Suite Upgrade Guide is clear on the upgrade path:
http://docs.sun.com/source/819-7561/planning.html
To quote:
While it is possible to upgrade all previous releases of Communications Suite software to Communications Suite 5, the only certified upgrades are from Java Enterprise System 2005Q4, Java Enterprise System 2005Q1, and Java Enterprise System 2004Q2. Upgrades from earlier releases are not documented in this Upgrade Guide.
Thus, upgrading directly from iPlanet Messaging Server 5.2 is not a certified way to go. From 5.2, you're supposed to go to 2005Q1 and then from 2005Q1 you can upgrade to 6.3. It's a two-step process. Headache, yes. But that's the certified route to take.