I'm not even rooted and gpay keeps breaking on crdroid for me, despite passing safetynet. I've given up and just got another credit card that I can use with my garmin watch that works every time without the hassle.
You can look for a service that provides a mail security gateway, or host your own. My personal solution is mimedefang milter on sendmail which will blow away any canned solution you will find. But you have to know what you are doing with it.
There is barracuda, but they are $$. Another option is proxmox mail gateway. Not as fast as mimedefang, but it has a nice gui.
They want to be the victims so badly.