I worked with Azure Boards and the entire TFS stack for multiple years and it’s a horrible experience. It’s very slow, buggy and especially the access-management is so poorly designed, most engineers had admin rights, because we tried for hours and ended it with “fuck it” and gave them admin rights, so they could do their job.
I have my own mailserver just for me and it wasn’t that complicated to be honest. I set it up with Mailcow in Docker in under a day. So far it has been stable with regular backups and updates through Lighthouse.
Maintenance comes down to 5 minutes every three months because somehow Let’s Encrypt and Mailcow don’t like each other and I have to renew the certificate manually.
Of course it costs an astronomical amount of money! It’s a space mission, what else would it cost?