SMTP 252 Cannot Verify User vs 553 Mailbox Name Invalid
SMTP 252 (Cannot Verify User) is a 2xx Positive Completion response, while 553 (Mailbox Name Invalid) 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, 553 means that the requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
Açıklama
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.
Gördüğünüzde
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.
Nasıl Düzeltilir
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.
Açıklama
The requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
Gördüğünüzde
When the sender or recipient address contains invalid characters, improper formatting, or violates the server's naming conventions.
Nasıl Düzeltilir
Check the email address format — ensure it follows the standard [email protected] pattern with valid characters. Remove any spaces, special characters, or encoding issues from the address.
Temel Farklar
252 is a 2xx Positive Completion response, while 553 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 553: The requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
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 553 when when the sender or recipient address contains invalid characters, improper formatting, or violates the server's naming conventions.
Hangisini Ne Zaman Kullanmalı
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 553 (Mailbox Name Invalid): Check the email address format — ensure it follows the standard [email protected] pattern with valid characters. Remove any spaces, special characters, or encoding issues from the address.