Understand why emails fail
A bounce isn't just a bounce. Is it a dead mailbox or a spam block? A DNS issue or rate limiting? Engagor classifies every failure by category, SMTP response pattern, ISP, and sender identity — so you know exactly what went wrong and what to do about it.
Deep failure diagnostics. Actionable root cause analysis.
Beyond bounce categories
Categories tell you what happened. SMTP patterns tell you why. Engagor analyzes raw SMTP response text to identify specific failure patterns and their root causes.
550 5.1.1
Invalid Recipient
"550 5.1.1 The email account that you tried to reach does not exist"
421 4.7.0
Rate Limit
"421 4.7.0 Try again later, closing connection"
550 5.7.1
Spam Block
"550 5.7.1 Message rejected due to content"
550 5.7.26
Policy
"550 5.7.26 This message does not pass authentication checks (SPF/DKIM)"
Provider-specific failure patterns
Different ISPs fail differently. Gmail is strict on authentication. Microsoft throttles aggressively. Yahoo watches content closely. See failure patterns per provider.
Gmail
45% of volumeMicrosoft
32% of volumeYahoo
15% of volumeWhich streams are failing?
Not all sender identities fail equally. Your transactional stream might be pristine while promotional has issues. See failure rates per identity to isolate problems.
Filter failures by identity to understand which sending streams need attention. Compare identities to spot patterns — maybe all B2C streams have higher bounce rates than B2B.
Ready to understand your failures?
See how deep failure diagnostics can turn bounces into actionable insights.