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
Discover how non-standard DKIM tag usage harms email deliverability. Learn to measure, diagnose, and fix issues with real-time verification and inbox.
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Use email verification and decay modeling to spot inactive subscribers, reduce bounces, and improve inbox placement. Clean your list with confidence.
Find and block forged emails sent from valid IPs using MailTester’s precision verification. Improve inbox placement and reduce fraud risk with real-time.
Avoid deliverability failure by understanding the hidden risks of launching a second email domain.
Stop emails from being rejected due to DKIM alignment failures. Learn how header domain mismatches break deliverability and how to fix them with real-time.
Discover how the SPF record size limit of 255 characters affects email deliverability and what to do about it. Verify your list today.
Learn how often DKIM keys should be rotated to maintain inbox placement, strengthen sender reputation, and prevent deliverability issues.
Discover how SPF misalignment hurts inbox placement in Gmail and Outlook. Learn to detect and fix it with real-time verification and deliverability.
Ensure your SPF records validate correctly across overlapping IPv4 and IPv6 ranges. Fix alignment issues that break sender reputation and inbox placement.
Use SMTP transaction log timestamps to track real-time email verification accuracy. Reduce bounces, improve inbox placement, and boost deliverability with.
Test mobile email delivery with SPF and DKIM alignment validation. Catch deliverability issues before they hit inboxes.
Ensure accurate delivery of international email addresses with our Unicode-compatible verification API. Check validity, catch-all, and risk in real time.
Stay sharp
Occasional, practical notes on verification and inbox placement. No spam — we'd be embarrassed.
