Gmail's sender guidelines require valid forward and reverse DNS. Missing or generic PTRs are a classic spam signal and cause outright rejections at many gateways.
The metrics that matter#
- Authentication pass rate: share of mail passing SPF, DKIM, and DMARC alignment. Healthy: 99% or higher.
- Spam complaint rate: Gmail enforces at 0.3%; stay under 0.1%.
- Hard bounce rate: under 2%; above 5% triggers platform reviews.
- Inbox placement: above 90% across major providers via seed tests.
- Engagement: click and reply rates by segment; opens are unreliable after Mail Privacy Protection.
Where to read them#
- Google Postmaster Tools for Gmail domain reputation, spam rate, and authentication.
- Microsoft SNDS and JMRP for Outlook.com IP reputation and complaints.
- Your ESP's delivery and bounce reports.
- DMARC aggregate reports for authentication by source.
Improving the numbers#
- Ask your hosting or ESP provider to set a PTR for each sending IP.
- Use a hostname under your domain (mail1.example.com) rather than the provider's generic name.
- Create the matching A record so forward and reverse agree.
- Use the same hostname in the SMTP HELO/EHLO banner.
Frequently asked questions#
Can I set PTR records in my own DNS?
No. PTRs live in the IP owner's reverse zone. Your hosting provider or ESP sets them, though some offer self-service.