552
SMTP Error 552: Message Size Exceeds Fixed Limit
Permanent failure
Medium severity
Content
RFC 5321
What it means
SMTP Error 552 means “Message Size Exceeds Fixed Limit.” Your email message (including attachments) exceeds the maximum size limit set by the receiving server. Most providers allow 25-50MB but some organizations set lower limits. Reduce attachments or use file sharing links instead.
At a glance
Code552
Bounce typeHard (permanent)
SeverityMedium
CategoryContent
What to doSuppress the address; do not retry
StandardRFC 5321
552 5.3.4 Message size exceeds fixed limitWhat does 552 mean?
SMTP code 552 means your email message is too large for the receiving server to accept. This includes the total size of the message headers, body, and all attachments (after Base64 encoding, which increases attachment size by roughly 33%). The size limit varies by provider and organization.
Gmail and Microsoft 365 generally accept messages up to 25MB. Google Workspace allows up to 50MB for internal messages. However, many corporate mail servers set lower limits, sometimes as small as 5-10MB. When sending large files, it is better to use file sharing services (Google Drive, OneDrive, Dropbox) and include a link in your email rather than large attachments.
How 552 plays out
Your server attempts delivery
The recipient server returns a permanent
552 rejectionThis is a hard bounce: the message will not be accepted as sent
Suppress the address and fix the root cause before resending
Where 552 sits: soft vs hard bounce
| Soft bounce (4xx) | Hard bounce (5xx) | |
|---|---|---|
| Nature | Temporary | Permanent |
| SMTP class | 4xx | 5xx |
| What to do | Let it retry | Suppress the address |
| Recoverable? | Often | No |
| 552 is | ✓ this code |
Common causes of 552
- Attachments are too large for the receiving server limit
- Base64 encoding increased the attachment size beyond the limit (adds ~33%)
- Multiple attachments combined exceed the size limit
- Embedded images in HTML email contributing to message size
- Organization has set a conservative message size limit
How to fix 552
- Compress attachments or reduce image resolution before sending
- Use file sharing services (Google Drive, OneDrive, Dropbox) and include a link instead
- Split the message into multiple smaller emails if necessary
- Remove unnecessary embedded images from HTML email
- Check the receiving server SIZE limit in the EHLO response before sending
Frequently asked questions
What does SMTP error 552 mean?
SMTP error 552 means "Requested mail action aborted: exceeded storage allocation." This permanent error is returned when the email you sent is too large for the recipient's server to accept, or when the recipient's mailbox has exceeded its storage quota and cannot receive new messages. It is a hard bounce, meaning the server will not retry delivery automatically.
What is the maximum email size for Gmail, Outlook, and Yahoo?
Gmail allows a maximum message size of 25 MB for both sending and receiving, including all attachments after MIME encoding. Microsoft 365/Exchange Online has a default limit of 25 MB, though some older Exchange configurations default to 10 MB. Yahoo Mail also enforces a 25 MB attachment limit. Importantly, MIME encoding increases file size by approximately 33%, so a 20 MB attachment may actually exceed the 25 MB limit once encoded and attached to the email.
How do I fix a "552 message size exceeds fixed maximum" error?
To fix this error, reduce the total size of your email by compressing attachments, using lower-resolution images, or removing unnecessary files. If your attachments are large, upload them to a cloud storage service like Google Drive, Dropbox, or OneDrive and include a sharing link in your email instead. For Gmail, files over 25 MB are automatically converted to Google Drive links. If you are an administrator, you can increase the maximum message size on your mail server, though the recipient's server limit will still apply.
Can a 552 error mean the recipient's mailbox is full?
Yes, a 552 error can indicate that the recipient's mailbox has exceeded its storage quota, not just that your message is too large. When a mailbox is full, the server returns 552 because it cannot allocate storage for any new message regardless of size. In this case, the recipient needs to delete old emails or upgrade their storage plan before they can receive new mail. As a sender, you can try resending after some time or contact the recipient through alternative channels to alert them.
Why does my email bounce even though my attachment is under 25 MB?
Your email may bounce because MIME encoding, which is required for email transmission, increases the effective size of attachments by approximately 33%. A file that is 20 MB on your computer becomes roughly 27 MB after encoding, pushing it over the 25 MB limit. Additionally, the limit applies to the entire message, including the email body, HTML formatting, inline images, email signatures with logos, and the full reply thread, not just the attachment alone. To stay within limits, keep raw attachments under 18-19 MB to account for encoding overhead.
Related bounce codes
Sources & further reading
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026
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