what will be the basic thing to do Upgrate Email Extender

What is your current version and what version are you going to ?
What is your environment ?
There is a forum post with some information about Patch 655.
There is a "Patch 655 Release notes" from July, 2008 and it has some good information.
The EX Installation Guide has a Chapter on "Updating EmailXtender".

http://powerlink.emc.com/nsepn/webapps/btg548664833igtcuup4826/km/live1/en_US/Offering_Technical/Technical_Documentation/300-003-393.pdf

Above is the link for the Compatibility Guide. You can download it from site and see the compatibilities.

Hi Ramsy,

Once you will finish downloading the patch kit you want to upgrade to, under documentation folder there is a copy of release notes. Release notes has a section called "Before you upgrade to this release", this should have all the steps documented for you to follow to do the upgrade. It will be referencing to EX install guide time-to-time which you can find again in the same folder where you found the release notes.

Thanks,
Raj