Fix PTR and HELO Alignment Warnings

PTR and HELO matter most when you send from infrastructure you control or from a provider using dedicated hosts.

What should align

  • The sending IP has a PTR record
  • The PTR hostname resolves forward to the same IP
  • The SMTP server announces a sensible HELO or EHLO hostname

Common issues

  • No PTR at all
  • PTR points to a generic or outdated host
  • HELO announces localhost or another non-public host
  • Forward and reverse DNS do not match

Practical fix

  1. Set PTR on the outbound IP.
  2. Use the same hostname in the SMTP daemon greeting.
  3. Confirm forward DNS resolves back to the sending IP.

You will often see PTR and HELO warnings together. Fix them as one infrastructure issue rather than one-by-one.