I have run it on Vultr, Frantech, and Linode. The real problem I find is most people want their mail server to instantly have good reputation, and mail simply doesn't work that way. You set it up, use it, and over time it earns its reputation, even if the address range is "bad". After the good reputation is achieved, migrate a domain to the server and send an email to one of the oligarch-owned servers and usually it will inbox and you're good to go so long as the server (i.e., user accounts) are not compromised and puke spam.

I do recommend editing Postfix to not filter out Spamhaus and instead configure Spamassassin to assign large points to Spamhaus listed domains. I realized this when the Dovecot list was being flagged by Spamhaus as spam and the list admin (with a dovecot.org email address) informed me that his server never sent spam and they owned the IP address and could not get anyone at Spamhaus to respond. If an email blacklist manager can't provide a meaningful way even for dovecot.org to be removed from a blacklist, and especially when there is no clear route for an admin to fix issues and be removed from a blacklist, then the blacklist cannot be a trusted gatekeeper for a mail server, which is how the Mail-in-a-Box project and many admins configure their servers.

If you don't have a good IP reputation or blocked ports, just use a relay such as mailgun or amazon ses for outgoing mails. Very easy to setup in mailcow.