What are some other options in this space?

What I need:

- Focus on transactional email.

- Support for inbound emails, sent to us via POST webhook.

- Good developer documentation and overall good product obviously.

- DKIM, SPF and DMARC support.

- Decent UI to troubleshoot delivery problems, i.e. easy to inspect the status for any one email.

- Happy to pay for it, price not a big factor.

I've looked at Mailgun, but happy to hear other suggestions.

I now use Postal Server for all my SaaS, which is self-hosted via docker, and has all those those features. The good thing is your maintain the IP reputation yourself and your not paying exorbitant prices when sending large volumes of transactional emails (really it's just the cost of the server you install it on).

https://github.com/postalserver/postal