The Blog
Hard-won lessons on email verification, inbox placement, and keeping your sender reputation spotless — from the team that's been verifying email since 2000.
Anti-spam laws and compliance: CAN-SPAM, GDPR, CASL
Learn how received headers expose sender IP and what you can do to protect privacy. Reduce deliverability risk with real email verification.
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Discover how clipped email addresses reduce engagement and harm sender reputation. Verify your list with MailTester’s 98.9% accurate tool to fix it.
Stop AT&T SBCGlobal and BellSouth emails from going to spam. Fix deliverability issues with real verification, inbox placement tests, and list hygiene.
Discover whether Gmail uses greylisting to delay email delivery. Learn how it affects senders, and how MailTester’s inbox placement testing helps you.
Uncover how spam filters analyze received headers to detect abuse. Learn what these headers reveal, why they matter for deliverability, and how MailTester.
Stop inbox placement drops after a sudden subscriber surge. Use real-time verification and inbox testing to maintain sender reputation and avoid spam.
Stop 450 4.1.1 recipient address rejected errors with real-time email verification. Reduce bounces, improve deliverability, and clean your list with 98.9%.
Decode the Proofpoint 554 rejected message. Learn why emails fail, how to fix it, and prevent bounces with real-time email verification.
Discover how spintax impacts cold email deliverability and spam filter detection. Learn why real email verification prevents bounces and improves inbox.
Fix Yandex Mail DMARC forwarding failures with real-time verification. Test inbox placement, detect invalid addresses, and reduce bounces with.
Ensure your Microsoft 365 auto-forwarded emails don't trigger spam filters. Learn how SRS sender rewriting maintains deliverability and protects sender.
Discover real-world mail stream types with clear examples. Reduce bounces, improve inbox placement, and optimize your email workflow with verified address.
Stay sharp
Occasional, practical notes on verification and inbox placement. No spam — we'd be embarrassed.
