Mailcow dockerized is great if you would like to host yourself, but dont want to spend too much time building or upgrading.
The problems you end up with is dealing with the big fish in this space. For instance, Microsoft are currently blocking all/most/a lot-of mail from Linode IPs and have been since 21 Dec regardless of individual server reputation[0].
[0] https://www.linode.com/community/questions/22287/550-57511-a...