SMTP 450 Mailbox Unavailable vs 535 Authentication Failed
SMTP 450 (Mailbox Unavailable) is a 4xx Transient Negative response, while 535 (Authentication Failed) is a 5xx Permanent Negative response. 450 indicates that the requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction. In contrast, 535 means that the authentication credentials provided are invalid. The username, password, or authentication mechanism was rejected by the server.
विवरण
The requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction.
जब आप इसे देखें
When the recipient's mailbox exists but is currently locked, busy, or subject to greylisting. The server is asking you to try again later.
कैसे ठीक करें
Retry delivery after a few minutes. If using greylisting, the second attempt will typically succeed. For persistent failures, check if the recipient's mailbox is full or disabled.
विवरण
The authentication credentials provided are invalid. The username, password, or authentication mechanism was rejected by the server.
जब आप इसे देखें
After submitting incorrect credentials via the AUTH command. The username or password does not match any account on the server.
कैसे ठीक करें
Double-check your username and password. If using an app password (e.g., Gmail, Outlook), ensure it is current and has not been revoked. Also verify the correct SASL mechanism (PLAIN, LOGIN, etc.).
मुख्य अंतर
450 is a 4xx Transient Negative response, while 535 is a 5xx Permanent Negative response.
SMTP 450: The requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction.
SMTP 535: The authentication credentials provided are invalid. The username, password, or authentication mechanism was rejected by the server.
You encounter 450 when when the recipient's mailbox exists but is currently locked, busy, or subject to greylisting. The server is asking you to try again later.
You encounter 535 when after submitting incorrect credentials via the AUTH command. The username or password does not match any account on the server.
कब किसका उपयोग करें
For 450 (Mailbox Unavailable): Retry delivery after a few minutes. If using greylisting, the second attempt will typically succeed. For persistent failures, check if the recipient's mailbox is full or disabled. For 535 (Authentication Failed): Double-check your username and password. If using an app password (e.g., Gmail, Outlook), ensure it is current and has not been revoked. Also verify the correct SASL mechanism (PLAIN, LOGIN, etc.).