Google Apps to Zimbra Migration

[braleigh]

Senerio:

I would like to migrate to Zimbra from Google Apps.

We currently have Google Apps host our email at example.com and our MX records route mail to them.

I need to keep my old email addresses i.e. user@example.com who gets thier email at google should get their email at user@example.com within Zimbra after they are migrated.

Its getting mail in the Zimbra account when the MX record is pointing to Google that is throwing me.

What would be the step by step process to this migration as far as MX, DNS, example.com, etc. I can handle the mail box migration.

Should I setup Zimbra to be example.com also?

Also the user migration will be a group of users at a time. Not everybody at once.

Thanks in advance.