External MX record / Mail server

It is possible to set external mail on server by setting MX record of the server dns to point to external IP. Another method will be removing the dns of the domain from the server and let the DNS be resolved on the external managed DNS.

If you have Postfix configured for your smtp, you will need to set the virtual-transport of the domain to another place.

Example:

domainname: exmaple.com, transport: smtp:ASPMX.L.GOOGLE.com:25

If you are running virtual domain support with mysql for postfix, you may find the configuration in /etc/postfix/mysql-virtual_transports.cf , stating the table in mysql to change.

More info:

http://www.postfix.org/postconf.5.html#virtual_transport