Blogs
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DMARC
Should You Send Email Marketing from a Subdomain or Your Root Domain?
A clear framework for deciding between subdomain and root domain email sending, with DMARC, SPF, and DKIM implications for each choice.
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DKIM
What Happens to DKIM When You Migrate DNS (and How to Recover)
DNS migrations can break DKIM and tank email deliverability. Here is what goes wrong, how to diagnose it, and how to prevent it on your next DNS change.
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Deliverability
Why Changing a User's Password Does Not Log Them Out of Outlook Web Access
A password reset does not automatically terminate an active Outlook Web Access session. Here is what admins need to know about OWA session invalidation and the real steps that actually end an attacker's access.
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Can Warming Up a Domain Too Aggressively Hurt Email Deliverability?
Sending volume too fast during warm-up triggers ISP spam filters. Learn the proper ramping schedule, recovery steps, and authentication best practices.
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SPF
Why Brevo SPF Causes Permerror at Yahoo and How to Fix It
When you send transactional email through Brevo using your own domain, strict receivers like Yahoo reject it with SPF permerror. Here is why it happens and how to configure Brevo correctly so your emails deliver.
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SPF
How to Add Multiple Email Services to Your SPF Record Without Breaking Authentication
Adding Brevo, SendGrid, and other third-party senders to your SPF record can quickly exceed the 10-DNS-lookup limit and break email authentication. Here is how to count your lookups, consolidate includes, and keep your SPF record working.
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DMARC
What to Do When a Vendor Sets Your DMARC Policy to Reject Overnight
A step-by-step troubleshooting guide for IT admins facing email breakage after a vendor changes their DMARC policy to reject. Covers diagnosis, immediate fixes, and prevention.
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DMARC
How to Validate DMARC Record Syntax Before Publishing
A DMARC record that looks fine can still break your email. Copy a template, miss a semicolon, publish it, and three days later your marketing emails start bouncing. The fix is not complicated.
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DMARC
RFC 9989 Drops DMARC’s Public Suffix List Dependency: What Practitioners Need to Know
RFC 9989 changes how DMARC validates multi-level domains by removing its dependency on the Public Suffix List. Here is what changed, who it affects, and whether you need to act.
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Deliverability
How to Fix the 550 5.7.134 Error When External Senders Email Exchange Online Moderated Mailboxes
The 550 5.7.134 error blocks external senders from emailing Exchange Online moderated mailboxes. This guide explains why it happens and gives you four ways to fix it.