secure mail from wordpress website on virtualmin to a google cloud server using non standard port

hi guys,
i need to get this image straight in my head…i have been spending a lot of time away from web stuff lately and my head is cloudy…

google cloud doesnt allow mail on standard ports. So if sending mail to other clients, i need to use a mail relay. Having said that, if i am using my own website contact form to send emails to my own email account (for the website domain) on virtualmin, can i simply have the website send emails to my domain email account using a custom port?

If so, and i think i would like to use smtp, what is the procedure for doing this (just need to get this right in my head)

Do i need to create zone file records for the email address as well? If so, do i do this at the registrar or just on my virtualmin server (i am not running my own dns…just using the registrar’s at present)