Blog
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DMARC
SPF, DKIM, and DMARC for Cold Email: A Simple Explanation
<p>Cold email authentication doesn't have to be confusing. Here's what SPF, DKIM, and DMARC actually do — plain and simple, with cold email specifically in mind.</p>
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SPF
SPF at 10 Lookups: How to Manage the Limit as You Add Vendors
Running out of SPF lookups? Here is how to reduce your SPF record's dependency count, flatten your record, and govern new vendor additions without breaking authentication.
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DMARC
Why Google Calendar Invite Responses Get Blocked After You Set DMARC to p=reject
Google Calendar sends response emails as the attendee, not as calendar.google.com. This fails DMARC p=reject. Here is how to fix it.
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DMARC
Why Your Legitimate Emails Get Rejected After Setting DMARC to p=reject
You tightened your DMARC policy to reject. Now your CRM, support tool, or marketing platform cannot deliver email. Here's why and how to fix it without opening yourself back up.
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DMARC
How to Set Up SPF, DKIM, and DMARC for Your Small Company Email
Proper email authentication doesn't require an IT team. Here's a practical, step-by-step guide to setting up SPF, DKIM, and DMARC for a small company with a simple setup.
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DMARC
Why Your Cold Emails Go to Spam Even When SPF, DKIM, and DMARC Are "Set Up"
<p>Cold emails landing in spam despite having SPF, DKIM, and DMARC configured? The problem is almost always misconfiguration, not authentication. Here's what to check.</p>
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DKIM
DKIM2 Is Coming: What Email Administrators Need to Know in 2026
<p>DKIM2 is a draft email authentication standard with replay defense, ordered chain-of-custody signatures, and modern crypto. Here is what changes and what it means for your email setup.</p>
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DMARC
How to Manage DMARC Across Multiple Domains Without It Becoming a Full-Time Job
<p>Managing DMARC across multiple domains is an operations problem, not a technical one. Here is the framework and tooling that makes it survivable.</p>
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DKIM
Why Short DKIM Keys in 2026 Are a Real Security Risk, Not Just a Best Practice Warning
<p>384-bit and 1024-bit DKIM keys are crackable. When someone cracks your DKIM key, they can send authenticated phishing that bypasses DKIM — and DKIM keys do not auto-rotate.</p>
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DMARC
What Causes Both SPF and DKIM Failures in DMARC Reports (And When It's Safe to Move to p=reject)
Your DMARC report shows both SPF and DKIM failing on the same emails. Here's what causes it, whether it's normal, and how to move to p=reject safely when third parties forward your mail.