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Bounce Decoder: 552 5.2.3

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

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552 5.2.3 — Message Too Large for Mailbox

The 552 5.2.3 bounce means your email exceeds the recipient server's maximum message size. Learn how to reduce attachment size and fix this error.

🔴
Permanent Failure (Hard Bounce)
SMTP Code
552
Enhanced Code
5.2.3
Category
Message Too Large for Mailbox
Frequency
Very Common

🔢 Enhanced Status Code Breakdown: 5.2.3

Component Value Meaning
Class 5 Permanent failure
Subject 2 Mailbox status
Detail 3 Message Too Large for Mailbox

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

💬 What This Error Means

Your email was rejected because it exceeds the recipient server's maximum message size limit. This includes all attachments.

Common Causes

  • Large attachments (images, PDFs, archives)
  • Recipient server has a low size limit (some cap at 10 MB or 25 MB)
  • Base64 encoding of attachments increases size by ~33%

How to Fix This

  • Share large files via a file-sharing service (Google Drive, Dropbox, WeTransfer)
  • Compress attachments before sending
  • Split into multiple smaller emails if needed
  • Check the recipient server's published size limit

🏢 Provider-Specific Variations

Google Workspace / Gmail

Gmail has a 25 MB limit for received messages. Google returns 552 5.2.3 when this is exceeded.

📖 Google Workspace / Gmail documentation →
Microsoft 365 / Outlook

Microsoft 365 has a 25 MB default receive limit. This can be raised by Exchange admins up to 150 MB.

📖 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 5.2.3 Message size exceeds fixed limit
552 5.2.3 5ikgjh033ah00 Your message has exceeded the size limit for the target mailbox

🔗 Related Error Codes

552 5.3.4
Message Too Big for System

📚 Official Documentation

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

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