What does the 550 error mean when sending emails?

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description: 'Hashtags: #Spam #Blocked #Blacklist'
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# What does error 550 mean when I try to send emails?

The **550 Email error** is related to the **SMTP** protocol and commonly associated with recipient-side errors.

Below, we will present the error codes and their meanings:

1. **Email Error 550 5.1.0 Address Rejected.**                                                                                      Address rejected. This error message means that the recipient's server will not accept emails from you. This is likely because the recipient is blocking your email address.
2. **Email Error 550 5.1.1**.                                                                                                                       It means that the recipient's email address you entered is invalid or does not exist in the target domain. This occurs due to typos in the email address or incorrect recipient server settings.
3. **Email Error 550 Denied By Policy**.                                                                                                  It means that an email security software has blocked outgoing emails to prevent attackers from guessing addresses by sending randomly generated email addresses.
4.  **Email Error 550 5.4.1.**

    It means that the recipient's server does not accept emails from the domain you are using. This error usually occurs due to incorrect DNS configuration.
5. **Email Error 550 5.7.0 Message Size Violation.** Message size violation. This error occurs when your email contains a file that exceeds the allowed size limit.
6. **Email Error 550 5.7.1 Access Denied**.                                                                                                          It means that the email was rejected due to security policies or incorrect settings on the recipient's side.
7. **Email Error 550 Administrative Prohibition**.                                                                               It can mean any of the following:
   * The domain used by your SMTP server is on real-time blacklists.
   * The recipient uses a domain that is on real-time blacklists.
   * The SMTP server has a dynamic IP address.
8. **Email Error 550 Relay Not Permitted**.                                                                                                               It means that the recipient's server does not allow the server you are using to send the email.
9. **Email error 550 Quarantined / 550 Error Recipient Quarantined**.                                               It means your email was marked as spam and not delivered. You will also face the same error message if your email address is on a blacklist.
10. **Email error 550 SPF**.                                                                                                                        A mail server will check a domain's Sender Policy Framework (SPF) record to verify if a sender is valid or not. If you send email from an IP address not registered in SPF, you will receive this error message.
11. **Email error 550 reverse DNS**.                                                                                                    It means there is no reverse DNS record for the mail server's IP address or there is a discrepancy in records in the domain used to send the email.
12. **Email error 550 recipient unknown / no such user here**.                                                            It means the recipient's mail server cannot find the email account. This can happen due to typos in the email address.
13. **Email error 550 host unknown**.                                                                                                                                The SMTP server sends this message if the hostname specified in the email address is unknown.
14. **Email error 550 Authentication is required for relay**.                                                                      It means Simple Mail Transfer Protocol (SMTP) authentication is missing. To send outgoing mail, SMTP authentication must be enabled in your email client, with your username and password.
15. **Server error 550 or 550 Blocked Error**.                                                                                                             This error message appears when the recipient's email server blocks the email you are trying to send. This SMTP error code indicates the email will be redirected to the sender.
16. **Error 550 5.1.0 Address Rejected**.                                                                                                                    It indicates that the recipient's server does not accept emails from the sender (you) or the recipient's messages. This error appears if the email address or all Exchange Online emails are blocked by the recipient.
17. **Server error 550 this domain is not hosted here**.                                                                                      This is another common error. The server rejects the email sent when the recipient's username is not found or cannot be accessed. Other reasons include typos in the email address and MX records.
18. **Error 550 in Outlook**.                                                                                                                                    This error message is frequently associated with "550 Authentication is required for relay." It means your email server requires SMTP authentication to send emails, but the email client you are using has not been authenticated with your username and password.

**Possible solutions to the problems:**

*   **Check for typos in the email address.**                                                   The email error 550 can occur due to typos in an email address. Make sure the email address you entered is correct and does not contain extra spaces or spelling errors. There is also a possibility that the recipient provided you with an incorrect email address. Confirm this with them as well.

    Additionally, verify that your email address has been entered correctly and that your email has content. Some mail servers will reject an email that has no content in it.
* **Check if your email IP is blacklisted**                                                             If your email IP is on a DNS blacklist, most of your emails will not reach the recipient and will be rejected.
* **Try changing the email sending port**                                                                                 If your email application uses port 25 as the email sending port, servers may block the email as spammers often use port 25 to send unwanted messages. Try changing the port to 26, 465, 587, or 2525.
* **Check if IP filtering is enabled**                                                                                                 Your SMTP server may be configured to authorize users only from a specific set of IP addresses. If that is the case, you will not be able to send messages from other locations. You can quickly resolve this by contacting your mail server administrator.
* **Enable SMTP authentication**                                                                                                                        In most email applications, SMTP authentication is set up automatically. If the application does not set it up correctly, you will not be able to send emails. Fortunately, you can manually set up SMTP authentication.