Self-Hosted Main

I appreciate everyones opinion, and I'm aware of the pro's con's of self hosting email, regardless of platform. With that being said, I had a question about hosting email from home hardware but tunneling traffic from an external site.

So I want to host my own email, i've done before and found it very fun and useful. I hosted it on digital ocean, but never went too far with it, just propped up a server, sent a few emails, and shut it down I'd like to host it at home so I can make use of existing hardware.

What are my options for tunneling traffic so I don't have to expose my home IP or home network directly to the internet? and also obviously bypass the issue of most isp's blocking email. Also, are there any other services that I should consider to help route my email? I've heard of services such as external mail relays that help improve deliverability and reduce the chance of email being marked as spam or blocked.

I genuinely find email admin to be very interesting, and think self hosting would be a great way to keep advancing my skills and learn more about security, etc.