Not parent, but I'm in the same boat with the self-hosted email VPS. I usually use Thunderbird as a client though, but sometimes mutt.

- SpamAssassin does a wonderful job after training it about once every 3 years. I get almost no spam.

- I was able to send to most people from my VPS, but not Charter. Charter blanket-blocked my ip block. So I ended up setting up SMTP forwarding via sendgrid free tier (100 emails per day). Now I always get through.