New Registrations Emails not being sent

[KirkM]

For some reason, the new registration emails have stopped being sent. All other email functions of the store are fine - order confirmations, order status changes, forgot password, bulk email customers, etc. All of them work. Just the registration emails don't go. I did an upgrade to 4.2.3 from 4.2.2 to see if that would fix it, but it didn't.

Anybody else have this issue and, hopefully, a solution?

Thanks.

[KirkM]

Got it figured out. My server won't correctly use mail() and localhost for sending that registration email (although it is fine for bulk email and order status ???). When I switched to SMTP and the actual mailserver with authentication it worked.