Set Up PTR (rDNS), HELO/EHLO, and FCrDNS for Better Email Deliverability
Mailbox providers check reverse DNS (PTR), your HELO/EHLO hostname, and forward-confirmed reverse DNS (FCrDNS). Correct alignment here prevents spam flags.
1) PTR (rDNS)
From your VPS/hosting panel, set the reverse DNS of your IP to your mail hostname, e.g. mail.yourdomain.com.
2) Forward DNS (A)
Create an A record so mail.yourdomain.com resolves to your VPS IP.
3) Hostname & HELO/EHLO
- Set the server hostname to
mail.yourdomain.com(e.g.,hostnamectl set-hostname mail.yourdomain.com). - Ensure your MTA (Postfix/Exim) uses this hostname in HELO.
4) Verify FCrDNS
dig -x [YOUR.SERVER.IP] +short # PTR -> mail.yourdomain.com
dig A mail.yourdomain.com +short # A -> [YOUR.SERVER.IP]
If both directions match, FCrDNS is good.
FAQ
- Q: Does mismatch break deliverability?
A: Yes. Mismatches can trigger spam filters or rejections. - Q: Should the HELO name be an FQDN?
A: Yes. Use a fully qualified domain likemail.yourdomain.com.
