If you’ve received SMTP Error 552, it means your email could not be delivered because it either exceeds the recipient server’s size limit or the recipient’s mailbox storage is full.
This guide will:
- Explain what SMTP 552 actually means
- Help you identify the specific cause
- Show you how to fix the issue safely
- Clarify whether the problem is on your side or the recipient’s
By the end of this guide, you’ll confidently diagnose and resolve SMTP 552 errors without unnecessary support escalation.
What SMTP Error 552 Means
SMTP 552 is often a permanent rejection (hard bounce).
What This Error Usually Means
Unlike temporary delivery delays, a 552 response usually means:
- The recipient server rejected the message due to size limits or storage constraints
- The message will not retry automatically unless corrective action is taken
Extended error codes (e.g., 5.2.2, 5.3.4) provide the precise reason.
Why This Matters
Understanding the root cause ensures you fix the problem, not just resend the email and hope it works.
The Impact of Ignoring These Errors
- Prevent important emails from being delivered
- Trigger repeated bounce-backs
- Reduce email deliverability over time
- Cause clients or customers to lose trust in your communication
Step-by-Step Fix for SMTP 552 Error – Message Size / Storage Limit
Follow these steps in order.
1: Confirm the Full Error Message
Open the bounce notification.
Ensure it references:
- 552 5.2.2 Mailbox full
- 552 5.3.4 Message size exceeds fixed maximum
- 552 Message size limit exceeded
- 552 Storage limit exceeded
If a different SMTP code appears, consult the relevant guide.
2: Check the Total Email Size
SMTP 552 commonly occurs when the message exceeds size limits.
Check:
- Attachments
- Embedded images
- Email signatures with large graphics
Keep total email size under:
- 20to 25 MB (recommended safe range)
3: Reduce Attachment Size
If the message is too large:
- Compress files (ZIP)
- Split attachments into multiple emails
- Use cloud storage links instead
Then resend.
4: Verify Recipient Mailbox Storage
If the error references the mailbox quota:
- Ask the recipient to free up space
- If you manage the mailbox, increase the quota in the Control Panel or upgrade the package
Once storage is available, resend the message.
5: Scan Attachments (If Security-Related)
If the bounce mentions:
- Illegal attachment
- Virus detected
Then:
- Scan your device for malware
- Recreate the file
- Remove suspicious attachments
6: Review Delivery Logs (Basic Level)
Log in to:
- cPanel → Email → Track Delivery
- Plesk → Websites & Domains → Select your domain → Mail → Track Email Delivery
Confirm whether rejection was due to:
- Message size
- Mailbox quota
- Security policy
Quick Fixes for Common SMTP 552 Variations
SMTP 552 occurs when:
- Message exceeds maximum allowed size
- Recipient mailbox is full
- Server applies other limits, filters, or policies
1. 552 5.2.2 Mailbox Quota Exceeded
Example:
552 5.2.2 User mailstore exceeded quota
552 5.2.2 Mailbox full What It Means:
Recipient mailbox storage is full.
How to Fix It:
- Ask the recipient to free up mailbox space
- If you manage the mailbox, increase the storage quota via the Control Panel
- Resend the email once space is available
Reassurance: This does not affect your hosting or email account.
2. 552 5.2.3 / 5.3.4 Message Size Exceeded
Example:
552 5.3.4 Message size exceeds fixed maximum
552 Message size limit exceeded What It Means:
Your email plus attachments exceeds the server’s allowed message size.
How to Fix It:
- Compress attachments (ZIP/7z)
- Use cloud storage links for large files
- Keep total email size under 20–25 MB
- Split attachments across multiple emails if needed
3. 552-5.7.0 Illegal / Virus Attachment Detected
Example:
552 Virus found inside the email
552-5.7.0 Illegal attachment What This Means:
The server flagged an attachment as unsafe.
How to Fix It:
- Scan your device for malware
- Remove or recreate suspicious attachments
- Confirm the website and local devices are secure
Advanced (Optional) Fixes (For Technical Users)
Administrators, or Technical Users can resolve server-level size or quota issues.
1. Check Mail Logs
Exim:
grep "552" /var/log/exim_mainlog
tail -f /var/log/exim_mainlog Postfix:
grep "552" /var/log/maillog
tail -f /var/log/maillog Goal: Identify whether 552 is due to message size, mailbox quota, or illegal attachment
2. Review Mail Queue
exim -bp # Exim
postqueue -p # Postfix - Verify deferred vs. rejected messages
3. Check Mailbox Quotas
- For cPanel/WHM: /scripts/setquota
- Adjust quotas if mailboxes are full
4. Inspect Attachments & Security
- Scan attachments for viruses/malware
- Remove or recreate flagged files
Optional: Automate scanning with ClamAV or similar:
clamscan -r /home/mailuser/maildir 5. Test Sending CLI / Size Limits
swaks --to [email protected] --server mx.example.com --data "Subject: Test\n\nAttachment test" --attach largefile.zip - Confirm recipient server accepts message size
6. Monitor Server Resource Limits
- High-volume sending may trigger 552 if server enforces per-user or global limits
- Adjust Exim/Postfix message size limits carefully:
# Exim
message_size_limit = 26214400 # 25 MB
# Postfix
message_size_limit = 26214400 Before You Move On
Confirm:
- Total email size is within limits
- Recipient mailbox has enough space
- No unsafe attachments are included
- Verify no security or virus blocks are triggered
Then resend your message.
Next Recommended Steps
- Check full bounce details
- Verify the recipient address
- Compress attachments or use cloud links
- Confirm mailbox storage is sufficient
- Retry sending
If This Didn’t Work
Check for:
- IP address blocks
- Blacklist warnings
- Policy references from recipient servers
Next steps:
- Remove attachments and resend plain-text email
- Confirm SPF/DKIM are valid
- Contact the recipient postmaster if necessary
Common Mistakes to Avoid
- Resending without reducing size
- Ignoring the recipient mailbox quota
- Using unsafe attachments repeatedly
- Assuming the hosting or website is broken
- Misinterpreting extended 552 codes
SMTP 552 errors affect email delivery only, not hosting, domain registration, or stored mailboxes.
Empowering Insight
Email size limits include encoding overhead (approximately 30%). Always keep messages slightly below maximum limits to ensure delivery.
FAQs
Q. Is this error permanent?
Yes, usually a hard bounce. Action is needed to resend.
Q. Will my hosting or website break?
No, only the email delivery is affected.
Q. How do I know if my email exceeded size limits or recipient storage?
The extended 552 code (e.g., 5.2.2, 5.3.4) provides the specific reason.
Additional Resources
SMTP Error Codes
SPF/DKIM Setup Guide
Email Sending Limits Guide
Email Bounce Back Guide
Need Additional Support?
We’re Here to Help:
Understanding SMTP Error 552 and how to fix this doesn’t have to feel technical with this easy-to-reference guide. Stuck? Check out our Scope of Support, and then contact our Support Team for further clarity and guidance (https://1grid.co.za/contact-us/). We’re ready to see how we can help!