[bagels]

What're the best resources for testing and configuring this stuff?

[1over137]

For testing:

https://mxtoolbox.com/

For configuring:

https://www.cyber.gc.ca/en/guidance/implementation-guidance-...

[XCSme]

I wrote this blog post for myself for whenever I have to configure email again: https://www.uxwizz.com/blog/stop-others-use-your-domain-emai...

[YPPH]

For testing, I find https://www.mail-tester.com/ helpful.