I use this docker container[1] to host a mail server on Binary Lane, batteries are included. It took me some fiddling to get it working but I took notes, happy to share them.
I also intend to follow all the bulk mail best practices, SPF/DKIM settings, MX records, security measures, email etiquette, etc, to make sure that our organisation normal notification/newsletter to our members, would not be treated as SPAM.