[missedthecue]

I've noticed a lot of sites and orgs wont accept email domains that aren't gmail, hotmail, outlook, icloud, or yahoo.

[marcusb]

Interesting. I've used my personal domain name for email for almost 30 years and I've never had that problem.

[rkomorn]

Similar boat (~25 years) and, while I've run into some sites/services that rejected my domain, I'm pretty sure it's happened fewer than 5 times, total.

[missedthecue]

It's a tactic to prevent burner/spam accounts created using temporary emails