If I had to make one suggestion, I would use a trusted third party to relay outbound e-mail such as AWS SES, mxroute, sendgrid, mailgun, etc. When I was looking for a job a few years ago, I found many potential employers’ systems would flag my e-mails as junk or simply delete them, and I had to revert to gmail. My second suggestion is to properly set up TLS/SSL for security, and SPF, DKIM, and DMARC for maximum deliverability. I’m currently using a deprecated application, but I’ve been testing mailcow which seems alright.