I have a personal mail server that collects my mail, but use my "default" Comcast MX to send. I'm sure metric craptons of email flow through that, but a lot of ham does too, so I've never been blacklisted.

I'd suggest that rather than the goal being to instantly leave this service or that the instant that they offend you, that you envision your policy as one of being ready to leave if you ever need to. The biggest key to that is having your own domain name and using that as your email address. Right now having your own domain is the biggest superpower you can have on the net, even with the events of last week. Honestly, pretty much everyone reading this from the US ought to own a domain name and be using it at least for their email address, even if it's purely delegated to gmail for the time being. They're too cheap to pass up the flexibility they offer.

What prevents your domain name registrar from shutting you down arbitrarily?

Also, I'm not sure what you're referring to as Comcast MX, but if you mean a Comcast provided server, that's a huge privacy hole. If you mean your own server on a Comcast line, then your IP is leaked to everyone you email, which is also a privacy hole since it ties your IP directly to your identity.

"What prevents your domain name registrar from shutting you down arbitrarily?"

I did say "even with the events of last week". It's the biggest stick you can get right now. It doesn't make you invincible.

"If you mean your own server on a Comcast line, then your IP is leaked to everyone you email, which is also a privacy hole since it ties your IP directly to your identity."

I don't email out much. Everyone I email is pretty much already going to know I'm me. Comcast already has arbitrarily large amounts of surveillance they can perform on me, sitting here worrying about my "outbound email hole" is a waste of time.

Great advice! Exactly what I'm doing as we speak after reading this. I'm such a cheerleader for Google but after hearing about this a few times its starting to scare the crap out of me. F that. Not a good idea to let a multi-national entity control my access to EVERYTHING with zero customer service options.

I did this. If you comply with some basic stuff like DKIM and ptr you get 100% accepted on everything but hotmail. I don't know how to get hotmail/outlook to stop greylisting me consistently.

Wow, that seems ... anticompetitive.

Er, no, it seems anti-spam. The fact of the matter is, plenty of people use dime-a-dozen hosting to make spam bots. These days, you're better off using a reputable mail service as opposed to rolling your own, unless you have a fairly large company.

It is anti-spam, but it is also anticompetitive to block anyone that isn't gmail or an already known big player in that space. Apparently lots of people are having trouble setting up a mail server on their own without getting blocked by Google. Can you see that as a problem for the intent at large? I wonder what kinda marketshare gmail has.

It's probably a problem they aren't in a hurry to solve either.

I mean it's not that you're automatically blocked it's just that your server's score for sending email is nonexistent which means a high likelihood of being a spam server.

You have to spend a long time to build up a reputation to get places to mark your email as not spam. This is why many providers that allow you to do bulk email through them have multiple IPs and they only let the most behaved on their better reputation IPs.

It's probably a problem they aren't in a hurry to solve because there's no reason to solve it. Any decently-funded small business can afford to use proper web hosting (Er, I love Digital Ocean. But they aren't really "web hosting").

Google (and basically every other reputable email host _and_ every "independent" email host) are blocking mail from services that host cheap compute power. A lot of Azure and GCP email traffic would likely be blocked, not just Digital Ocean.

If you want to start an email service, use something that isn't a known platform for spammers.