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.
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552
5.2.3
Message Too Large for Mailbox
Very Common
🔢 Enhanced Status Code Breakdown: 5.2.3
| Component | Value | Meaning |
|---|---|---|
| Class | 5 | Permanent failure (Hard bounce) |
| 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 is a bit too heavy for the recipient's inbox! This usually happens when you've attached large photos, videos, or documents that exceed the maximum size they are allowed to receive.
Common Causes
- Large attachments like high-resolution images or large PDFs
- The recipient server has a strict limit (often 10 MB or 25 MB)
- The way email "packages" attachments for sending actually increases their size by about 33%
How to Fix This
- Instead of attaching files, try sharing them via Google Drive, Dropbox, or WeTransfer and sending a link
- Compress your attachments into a ZIP file to shrink them down
- If you have many photos, try sending them in multiple smaller emails
- Check the recipient's website to see if they list a maximum file size for their staff
📚 Official Documentation
Gmail has a 25 MB limit for received messages. Google returns 552 5.2.3 when this is exceeded.
📖 Google Workspace / Gmail documentation → Browse all Google Workspace / Gmail error codes →Microsoft 365 has a 25 MB default receive limit. This can be raised by Exchange admins up to 150 MB.
📖 Microsoft 365 / Outlook documentation → Browse all Microsoft 365 / Outlook error codes →📋 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
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