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SMTP Error 503

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Description: Bad sequence of commands. What does this mean? This is also very similar to SMTP Error # 501. The small difference in this, is due to the parameters or options being out of order from what the mail server expected. This is commonly seen when not authenticating the email account. How to fix SMTP […]

SMTP Error 504

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Description: Command parameter not implemented. What does this mean? This is another name or reference for SMTP Error # 502. Please reference it’s documentation. Related Articles: SMTP Error 214 SMTP Error 421 SMTP Error 450 SMTP Error 503 SMTP Error 541

SMTP Error 510

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Description: Invalid email address. What does this mean? This response is straight forward. One of the email addresses in the ‘TO:’, ‘CC:’, or ‘BCC:’ is incorrect (invalid). How to fix SMTP Error 510? Check all email addresses in your message, including (‘TO:’, ‘CC:’, and/or ‘BCC:’), for any misspelling. Related Articles: SMTP Error 214 SMTP Error […]

SMTP Error 449

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Description: A routing error. What does this mean? Also, like most other Microsoft Errors, this message leaves a lot to question. No official description is provided for this, however see the fix suggestion for possible further diagnosis. How to fix SMTP Error 449? Microsoft’s official suggestion for diagnosing and attempt to resolve the issue, is […]

SMTP Error 450

Category: Other
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Description: Requested mail action not taken: mailbox unavailable (e.g., mailbox not found, no access, or command rejected for policy reasons). What does this mean? Generally errors ending with 0 are going to be the least specific. This error is no exception. This has many meanings or specific possibilities. The most common possibilities include: The recipient […]

SMTP Error 451

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Description: Requested action aborted: error in processing. What does this mean? When attempting to process the message, the receiving mailserver’s rules prevented it from processing it for delivery. Rules such as SPF verification can create this error. How to fix SMTP Error 451? Depending on the exact message given, it’s most likely related to the […]

SMTP Error 452

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Description: Requested action not taken: insufficient system storage. What does this mean? Your mail server is ‘overloaded’. This could be caused by too many messages attempting to send at once, the server being out of memory or storage space. How to fix SMTP Error 452? Review your current mail queue and log to ensure adequate […]

SMTP Error 455

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Description: Server unable to accommodate parameters. What does this mean? If for some reason the server is temporarily unable to accomodate one or more of the parameters associated with a MAIL FROM or RCPT TO command, and if the definition of the specific parameter does not mandate the use of another code, it should return […]

SMTP Error 471

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Description: An error of your mail server, often due to an issue of the local anti-spam filter. What does this mean? This description is pretty straight forward. Your server or (remote mail server)’s anti-spam filter has prevented this message from proceeding. How to fix SMTP Error 471? Attempt disabling outgoing anti-spam filters from your server. […]

SMTP Error 500

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Description: Syntax error, command unrecognized (This may include errors such as command line too long). What does this mean? The receiving SMTP mail server was unable to correct process the command(s) received. Also note, commands that are processed but not used will be handled with different response numbers. How to fix SMTP Error 500? The […]