I still have issues receiving emails. Especially from financial institutions. (Wells Fargo emails just... stopped. So I gave up and setup a gmail just for them.)
I have issues sending emails from my custom domain.
IRL I always have to explain that yes, my email address is YourCompany@MyDomain.com, but no, I don't actually work for YourCompany.
Over two decades, I have played whack a mole with a number of problems. Switching to a hosting provider that does not allow me to forward <any>@customdomain.com helped. It only allows explicitly forwarded email accounts, and setting up the email address explicitly passes most email validation tests, and I suspect the underlying IP is less likely to be blacklisted by fin tech that is extra careful about who they email.