First of all I want to congratulate all zimbra team as well as the forum members for their great support. Otherwise Icant run my zimbra for the last 20 months without any problem.
Iam using zimbra 6.0.1 working under 32 bit platform. Now I want to upgrade to the latest version under 64 bit platform.
How can I upgrade to RHEL 5 64 bit version. Is there any known problem while doing so.

Is it possible to migrate all my mails to this new platform?

Waiting for your suggestions.