SMTP help - different servers and subdomain

Domain is on an AWS Server.
Discourse is at a subdomain on a Digital Ocean droplet.
Cloudflare is in control.

I’m using Mailgun for the discourse because my main site is running on google workspace.

Should mailgun be subdomain.domain.org?
And should the records be on DO network or cloudflare?

Yes.

You just said cloudflare. You can use a dns check site to test that the changes you make are what the internet sees.

You can check the whois records to check what dns server is in charge. (To see if cloudflare is really in control).

Use the gray cloud (dns only) for your Discourse record.

Thanks for the reply @pfaffman doing some testing this morning. I was able to get it loaded on the subdomain server but now the issue is proper smtp handling.

What about smtp?

Got this figured out and going to try to write up a n00b tut.