SMTP 252 Cannot Verify User vs 552 Exceeded Storage
SMTP 252 (Cannot Verify User) is a 2xx Positive Completion response, while 552 (Exceeded Storage) is a 5xx Permanent Negative response. 252 indicates that the server cannot verify the user but will accept the message and attempt delivery. This is often returned in response to VRFY when the server intentionally hides user information. 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.
描述
The server cannot verify the user but will accept the message and attempt delivery. This is often returned in response to VRFY when the server intentionally hides user information.
何时出现
When using the VRFY command to check if a recipient exists. The server refuses to confirm or deny the address, typically as a spam-prevention measure.
如何修复
No fix needed — the server will still attempt delivery. If you need to verify addresses, contact the mail administrator or rely on bounce-back messages instead.
描述
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.
何时出现
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.
如何修复
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.
主要区别
252 is a 2xx Positive Completion response, while 552 is a 5xx Permanent Negative response.
SMTP 252: The server cannot verify the user but will accept the message and attempt delivery. This is often returned in response to VRFY when the server intentionally hides user information.
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 252 when when using the VRFY command to check if a recipient exists. The server refuses to confirm or deny the address, typically as a spam-prevention measure.
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.
何时使用哪个
For 252 (Cannot Verify User): No fix needed — the server will still attempt delivery. If you need to verify addresses, contact the mail administrator or rely on bounce-back messages instead. 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.