Others have mentioned Fastmail, and it really is great. But I don't think it's the final stop if you want transactional emails.
Decided to try out Cloudflare email routing[0], and have it routing to Fastmail and/or Gmail. I'm not using email workers for much yet, but it's a pretty cool feature.
I'd definitely recommend it as a super easy way to just get email working for a domain, and just route the emails to/from your existing email accounts.