Assume that you’ll have availability problems with email and engineer with that in mind.
The reason most just say "You're banned, bye" is because they don't want to do that work, and subsequently don't care about their users one bit.
I could say the same thing to you, you're making it sound harder than what it is. But if you're set to the mindset of saving money, I understand minimising work makes sense.
Of course they do. It’s just email/twitter/telegram/WhatsApp, and fraudsters are literally professional messaging automators. They open support cases, email execs, I have seen cases of them paying call center workers to call support lines and complain. Fraud is a serious business run by serious people, many of whom have a decade plus of experience.
You cannot attempt to stop fraud with manual effort if you operate at any kind of scale. Full stop.
> Assume that you’ll have availability problems with email and engineer with that in mind.
That goes for all dependencies, not just email. And not just third-party dependencies either.If PyStorm died today, I could carry on in VIM. I could rebuild my entire architecture on DO if AWS sours. If git takes a dump, I have four machines from which I could copy the code and migrate to e.g. mercurial. And if I get hit by a bus, my code is well documented and testable.