SMTP 451 Local Error vs 552 Exceeded Storage
SMTP 451 (Local Error) is a 4xx Transient Negative response, while 552 (Exceeded Storage) is a 5xx Permanent Negative response. 451 indicates that the requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command. In contrast, 552 means that the requested mail action was aborted because the recipient's mailbox has exceeded its storage allocation. Unlike the temporary 452, this is a permanent rejection for this specific mailbox.
Description
The requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command.
When You See It
When the receiving server hits an internal error such as a database failure, DNS lookup timeout, or anti-spam filter processing error.
How to Fix
Retry the message later. If you control the server, check its logs for the specific error — common causes include DNS resolution failures, disk I/O errors, or database connectivity issues.
Description
The requested mail action was aborted because the recipient's mailbox has exceeded its storage allocation. Unlike the temporary 452, this is a permanent rejection for this specific mailbox.
When You See It
When the recipient's mailbox is completely full and cannot accept any more messages. The recipient needs to delete old emails or increase their quota.
How to Fix
Notify the recipient through another channel that their mailbox is full. If you are the recipient, delete old messages or contact your mail administrator to increase the storage quota.
Key Differences
451 is a 4xx Transient Negative response, while 552 is a 5xx Permanent Negative response.
SMTP 451: The requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command.
SMTP 552: The requested mail action was aborted because the recipient's mailbox has exceeded its storage allocation. Unlike the temporary 452, this is a permanent rejection for this specific mailbox.
You encounter 451 when when the receiving server hits an internal error such as a database failure, DNS lookup timeout, or anti-spam filter processing error.
You encounter 552 when when the recipient's mailbox is completely full and cannot accept any more messages. The recipient needs to delete old emails or increase their quota.
When to Use Which
For 451 (Local Error): Retry the message later. If you control the server, check its logs for the specific error — common causes include DNS resolution failures, disk I/O errors, or database connectivity issues. For 552 (Exceeded Storage): Notify the recipient through another channel that their mailbox is full. If you are the recipient, delete old messages or contact your mail administrator to increase the storage quota.