Hi,
I will set up server with mailing application that is mailwizz/PMTA and implement like spf,dkim,ip rotation,dmarc. for good inbox delivery.
Email server security:-
SMTP authentication
Enable SURBL
Maintain local IP blacklists
Encrypt POP3 and IMAP authentication
SPF/DKIM installation
RDNS creation
Open Relay Disable
Exim mail server security tweaks
Thank you