I self-host e-mail, because I am stubborn - I have done it for 20 years. I would not recommend anyone do it if they aren't already, or if they well-and-truly want to be on call for their homelab.

So as not to reiterate, here's an HN comment where I described the most recent trial I endured with it: https://news.ycombinator.com/item?id=46297991

In the last 20 years, I've also run into problems like:

* My brand-new ISP wouldn't allow TCP port 25 inbound, and wouldn't relent. I had to go back to the old ISP.

* SPF became mandatory at Gmail, but I didn't get the memo, and Google started bouncing my mail one random day.

* My residential IP ended up on a "policy blacklist", one it could never get off because it's blacklisted by virtue of being a residential IP, not that it did something bad.

I host my email, my isp blocked mail ports too, my simple and reliant solution is to use 2 quite cheap VPS on different zones as front email servers, with haproxy and postfix forwarding, took some time to setup but works great and not dependent on isp rules.