I got a small PHP script using phpmailer that sends a mail to a specific adress. On my old server, that worked. On the new one, it doesn't. The script reports no errors but simply that the mail has been sent successfully, but it never shows up at the recipient.
Does anyone have any idea what might be configured incorrectly?
I tried using the email troubleshooter in WHM. That one reported no problems either.
I'd be very glad if anyone could help.
Edit: Was checking some stuff in WHM, and found this:
550 Access denied - Invalid HELO name (See RFC2821 18.104.22.168)