Mail sent like this won't be delivered anywhere with even the most basic spam filtering which includes blacklists of known spam-source IP address blocks like Digital Ocean/AWS/Heroku.
It's probably a problem they aren't in a hurry to solve either.
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.
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.
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.
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.
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.
