We are in the process of migrating three email accounts from a cPanel web-hosted server to Google Apps Gmail. With this, these users exclusively use POP3 to check their email using Microsoft Outlook and do not leave a copy on the server. This process is in part based on this post a post on cPanel forum (search Google: "google apps split delivery for domain cpanel forum" — 2nd link).
The current strategy is to perform the following:
Setup dual delivery with Google Apps as primary mail server, forwarding a copy to the legacy server (https://support.google.com/a/answer/178267?hl=en)
Setup email forwards for each user on the legacy mail server to forward email to the Google Apps test domain (only necessary when users on legacy mail server send emails to other legacy mail server users). Additionally setup the legacy mail server as a mail gateway. (https://support.google.com/a/answer/178332?hl=en)
Setup Google Apps Sync to perform the initial data import (e.g. Outlook mail to Gmail) and keep synced for all time.
There are two areas I am concerned:
For Step 3. The same email will exist in the Outlook inbox as well as in Gmail. Will this initial import duplicate emails?
Generally. Do I still need to add the Gmail IMAP account to Outlook if I am using Google Apps Sync?