When I change the email settings on v 8.1.2 to use my own SMTP parameters through our mailgun account, it won't send emails at all. The test email comes through fine, but customers do not get any confirmation emails or password reset emails etc. If you request a change of password on your account, it just comes up with a red error saying that an error occurred. This was working fine on 1.7.7.2 but since we upgraded to v8 it doesn't work. I'm on php v8.1.
Does this sound like a bug or is there something else I should try to get it working? I can't see anything in the server logs.