That's not my experience. MS Outlook seems to have it's off days, but email usually arrives just fine. That's even on Contabo's network, which is listed on that one "your ISP doesn't do enough to stop spam" blacklist Microsoft annoyingly refers to.

I don't see any spam in my inbox either, the little spam I do receive ends up in the spam box where it belongs.

Whatever mail setup Mailcow defaults to has worked great for me. Mailcow and mail-in-a-box have made the classic email setup very painless.