Blogs
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DMARC
Why Your SPF DKIM and DMARC Records Pass DNS Checks But Receivers Still Disagree
Your SPF DKIM and DMARC records pass every DNS checker. Yet some email receivers reject your messages. Here is why receivers disagree and how to diagnose which one has the correct result.
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Deliverability
What TLS Version Does My Mail Server Need in 2026?
TLS 1.0 and 1.1 are deprecated. Here is what mail server operators need in 2026.
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DMARC
Why DKIM and SPF Pass But DMARC Still Fails: Alignment Explained
SPF and DKIM can both pass while DMARC still fails. Here is why authentication and alignment are different things, and how to fix alignment failures.
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DMARC
Why Abandoned DMARC Reporting Endpoints Are a Security Risk
If your DMARC rua endpoint points to an expired or abandoned domain, your aggregate reports may be landing in a stranger's inbox. Here is how to audit your reporting endpoints before that happens.
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Deliverability
What TLS Version Do Mail Servers Need in 2026? A Practical Guide
Most major mail providers now require TLS 1.2 or higher. Here is what the standards say, what receivers actually enforce, and how to check your mail server TLS configuration.
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DMARC
DMARC Reject vs Quarantine: How to Choose and Roll Out Safely
This guide explains what p=reject and p=quarantine actually do, how to choose between them, and how to move from monitoring to enforcement without breaking legitimate email.
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Deliverability
How Many Mail Servers Refuse Non-TLS Connections? We Checked 366,000 of Them
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DMARC
How to Handle DMARC Failures Caused by Third-Party Email Senders
Third-party email senders often break DMARC alignment. Here is why it happens and how to fix it for good.
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DMARC
How Strict Should Your DMARC Policy Be? Real-World Risks of Each Level
Choosing between p=none, p=quarantine, and p=reject means balancing email security against the risk of breaking legitimate mail. Here is what actually breaks at each level.
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DMARC
Why You Still Get Backscatter NDRs Even With DMARC at Enforcement
Backscatter NDRs still arrive after DMARC enforcement because DMARC rejects mail at the receiving server, not the sending server. Third-party mail servers still send bounces to the From: address.