An OpenBSD E-Mail Server Using OpenSMTPD, Dovecot, Rspamd, and RainLoop (docs.vultr.com)
I actually do this, minus rainloop, and it works pretty great.
There have been multiple accounts created with the sole purpose of posting advertisement posts or replies containing unsolicited advertising.
Accounts which solely post advertisements, or persistently post them may be terminated.
I actually do this, minus rainloop, and it works pretty great.