I've been running my own Postfix (Dovecot, MySQL, Rspamd) server thanks
to these instructions
(https://thomas-leister.de/en/mailserver-debian-stretch/ ) for more than
a year without any issues.
I'm using a paid service (Mail Reflector) to handle the times my server
is down or (initially) to get the my mail server up and running.
I'd like set up another server as a backup and while there are some "How
To" out there, they seem to be 'ignoring' spam and/or security issues.
Could I just use the same approach I used when setting up my current
server with the exception of the following:
1. No virtual mailboxes on the backup
2. with an empty smtp_recipients_maps
3. with relay_domains = $mydestination mydomain.com
Thanks,
Leo