Once upon a time... our marketing director thought it was a good idea to send a mail campaign through our internal mail server... 30K+ emails. At once. That did not end well for the marketing dept. I was... annoyed. Highly. It took days to clean our mailserver and get our IP off of blacklists - and the sheer amount of bounces that were coming back for days. The poor server nearly died. Of course it was somehow 'my' fault.
Anyway... Setting up and running a mail server is a PITA, but I have been doing it for quite some time. I almost forget it's running. It just works. However, I am running off a business IP and try to avoid sending huge batches of email. The suggestion above about AWS SES is interesting. DMARC, SPF, MX records, spamassassin, postfix, dovecot, fail2ban, certificates, a server, firewall, ports, aliases, virtuals, forwards... make sure you backup whatever config you land on!
Thanks