Even if users’ email is handled by Google, there are cases where mail is generated by web site scripts, eg. forum notifications, mailing lists, etc. In some cases such scripts can be configured to use remote SMTP server, but in many cases they assume a local MTA is available (eg. PHP’s mail() function) – thus we do need to keep posfix on.
This is how to set it up:
For every existing server and sub-server – Uncheck the following: Edit Virtual Server -> Enabled Features -> Mail for domain enabled.
For every domain: Ensure that domain name is not listed in /etc/postfix/virtual– if it does then delete all lines that contain the domain, and finally run postmap /etc/postfix/virtual
Uncheck the following: Virtualmin -> System Settings -> Features and Plugins ->
Mail for domain
New mailbox signup.
Select (check) and click Disable Now and On Boot the following: Webmin -> System -> Bootup and Shutdown ->
Then simple add these DNS MX entries: (remove old entries if they are present)
example.com. 300 IN MX 0 aspmx.l.google.com.
example.com. 300 IN MX 1 aspmx2.googlemail.com
example.com. 300 IN MX 2 aspmx3.googlemail.com