How to remove an account from Google Apps for Business email, but still keep the Google account for single sign on, etc.?

Question

I've got a Google Apps for Business account where 3 domains emails are managed.

One of the domains emails I want to move to another provider.

My current thought was to :

1. Create the email account with the new provider
2. Setup the IMAP and SMTP settings for the account in a desktop email client like mac mail (where I would also have the google apps email account of the same name setup)
3. Manually drag and drop the emails from the Google Apps account to the new IMAP account
4. Once above complete, I would change the MX records with my host (the domain is not hosted with Google) to point to the new IMAP account and away from Google apps.
5. Delete the account from Google Apps (I could keep the email account with Google Apps, but in this instance part of the reason for the move is to completely remove the account from Google Apps)

Question: I still want to use my Google account (single sign on, etc.) with the email address I move. If I delete the Google account as per step 5 above will I lose all the data stored with my Google account or can I transfer the Google Apps account to a standard Google account without Google Apps hosted email?

Answer 1

I have recently moved from Google to fastmail.

I used offlineimap with two remote repositories to sync emails from Gmail to fastmail.

My Google App is free (created pre charging point) so I didn't close it. All MX records are pointing at the fastmail server. From time to time, when I log into GMail, I see emails in my Inbox that I don't expect to be able to receive, mainly sent from friends GMail accounts. I suspect that when a GMail account sends an email to a domain registered with Google apps, Google does not bother checking the MX record (perhaps optimisation) and sends it straight into the GMail inbox associated with the account.