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.
Email authentication: SPF, DKIM, DMARC, BIMI and MTA-STS
Master the DMARC pct tag rollout in 2026 with precise, step-by-step guidance. Reduce bounces, avoid spoofing, and strengthen sender reputation with.
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Detect and block lookalike domains before they harm your sender reputation. Use real-time email verification with MailTester to prevent inbox placement.
Restore your cold email domain reputation after spam. Use real-time verification, inbox testing, and list hygiene to prevent bounces and rejections.
Secure your email with a proven Postfix DKIM signing setup using OpenDKIM. Learn step-by-step how to authenticate your outbound mail and boost inbox.
Stop inflated click metrics from Mimecast URL Protect. Learn how bot clicks distort analytics and how MailTester’s email verification cuts through noise.
Learn how to optimize your cold email cadence for Google and Microsoft mailboxes. Improve inbox placement and reduce bounces with proven.
See if Gmail shows a blue checkmark when the email uses CMC. Learn the real technical truth and how to verify email validity with MailTester’s 98.9%.
Understand what a DKIM replay attack is, how spammers exploit signed emails, and how to detect it.
Learn why cloud providers block outbound port 25 by default, how it affects email deliverability, and what to do about it.
Fix failed transactional emails in WordPress with Brevo SMTP relay. Verify sender reputation, test inbox placement, and reduce bounces with real-time.
Discover how ESP seed tests and independent placement tests differ in real-world deliverability testing.
Fix duplicate email removal issues caused by local part case sensitivity. Learn how to normalize emails and avoid false duplicates in your list hygiene.
Stay sharp
Occasional, practical notes on verification and inbox placement. No spam — we'd be embarrassed.
