Does such a service exist ?
If not, I've had good luck with Linode in the past. No longer a current user, but was happy with their service when I was.
But as @joezydeco says, running your own email infrastructure is fraught with difficulties. If you already know all this and know how to deal with the issues, have at it. If not, you might want to do some research and really consider whether or not it's a good idea to try doing that yourself.
However Microsoft does not allow outbound SMTP port 25 from Azure by default. It is possible to get them to allow it, but I do not know their criteria, as I've never done it.
I try to avoid running my own mail infrastructure. Even now when I need scripts to send mail, for reports and such, I'll use a service like Sendgrid instead of mucking about with Sendmail. It is just too easy to do it wrong and end up in a black hole.
Running your own mail server is tricky. I pulled my hair out trying to get all the authentication shit in place to allow gMail to accept incoming messages. Definitely not a beginner-level task.
OCI is "free forever", with quite capable x86-64 and ARM VMs.
GCP also works great.