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Bounce Decoder: 552 5.3.4

SPF, DKIM, DMARC, FCrDNS, Blacklists & Inbox Prediction

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552 5.3.4 — Message Too Big for System

The 552 5.3.4 bounce means your message exceeds the receiving mail system's overall size limit. Learn how to reduce email size and fix this bounce.

🔴
Permanent Failure (Hard Bounce)
SMTP Code
552
Enhanced Code
5.3.4
Category
Message Too Big for System
Frequency
Very Common

🔢 Enhanced Status Code Breakdown: 5.3.4

Component Value Meaning
Class 5 Permanent failure
Subject 3 Mail system status
Detail 4 Message Too Big for System

Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.

💬 What This Error Means

Your email is too large for the receiving mail system to handle. Unlike 5.2.3 (which is per-mailbox), this is a system-wide size limit that cannot be overridden for individual accounts.

Common Causes

  • Large attachments pushing the message over the system limit
  • Embedded HTML images (base64-encoded inline images)
  • Recipient server has a very low system-wide size limit
  • Message size includes all headers plus body plus attachments

How to Fix This

  • Use file-sharing services (Google Drive, Dropbox, OneDrive) instead of attachments
  • Compress all attachments into a single ZIP before sending
  • Link to images hosted online instead of embedding them in the email
  • For large files, consider a dedicated file transfer service

🏢 Provider-Specific Variations

Google Workspace / Gmail

Google Workspace has a system-wide 25 MB send limit and 50 MB receive limit. Exceeding these results in 552 5.3.4.

📖 Google Workspace / Gmail documentation →
Microsoft 365 / Outlook

Microsoft 365 default system limit is 25 MB. Enterprise plans can configure up to 150 MB per organisation.

📖 Microsoft 365 / Outlook documentation →

📋 Real-World Example Messages

These are real bounce message formats you might receive. Paste yours into the Bounce Decoder for instant analysis. 

552 5.3.4 Message size exceeds fixed maximum message size
552 5.3.4 Message too large

🔗 Related Error Codes

552 5.2.3
Message Too Large for Mailbox

📚 Official Documentation

↗ Google message size limits ↗ Microsoft 365 message size limits
🔍

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