Free SMTP Email Bounce Code Analyzer & Remediation Tool
Paste any SMTP bounce code (550, 554, 421, 5.7.1). Determine hard vs soft bounce, root cause, and step-by-step fix to protect domain reputation.
Why Cold Outbound Teams Use Our Free Bounce Analyzer
5xx Hard Bounce vs 4xx Soft Bounce classifier
Google & Microsoft error code database
Immediate remediation checklist
Email Deliverability Standards (US & UK Outbound Guidelines)
In February 2024, Google Workspace and Yahoo introduced strict anti-spam enforcement rules that mandate proper SPF, DKIM, and DMARC authentication for all outbound mailboxes. If your DNS records have syntax errors or exceed the 10-lookup threshold, incoming mail servers will silently route your cold outreach into the Spam folder or reject connections entirely.
Requires valid physical postal address in signatures, accurate From header identification, and clear opt-out mechanics.
Permits B2B outreach under legitimate interest when targeted to relevant corporate decision-makers with authenticated sender identity.
Frequently Asked Questions About Bounce Analyzer
What is the difference between a Hard Bounce and a Soft Bounce?
A Hard Bounce (5xx) is permanent (e.g. invalid mailbox, mailbox does not exist). A Soft Bounce (4xx) is temporary (e.g. recipient mailbox is full, server rate limiting).
What bounce rate is acceptable for cold email campaigns?
Keep your bounce rate strictly below 2%. If your bounce rate exceeds 3-5%, Google and Microsoft will throttle or ban your domain.
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Get fully authenticated, pre-warmed business inboxes on your own domains with dedicated US & UK IPs for just $4.00/mailbox/month.