How to fix email error 550

Matthew Adams
by Matthew Adams
Windows & Software Expert
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Email error 550 can arise in various email client software, such as Outlook and Mozila Thunderbird. The error arises when some users send emails with client software. Although the exact error messages that pop up might vary slightly, they will all include the 550 error code. As a consequence, users can’t send emails to specific recipients with their client software.

Error 550 is the SMTP (Simple Mail Transfer Protocol) error for sending emails. The SMTP server hasn’t sent the email when error 550 arises as the recipient’s mailbox isn’t available. That can be due to few things, and in some cases it might actually be an issue that the intended recipient, not the sender, can fix.

How Can Users Fix Email Error 550?

1. Check for Email Address Typos

Error 550 can arise due to email typos. So, double-check you’ve entered the exact email address. Make sure there are no typos or spaces in the email address before clicking the send button.

Email address typo email error 550

2. Send the Email a Day Later

Although not likely, the recipient’s server might be down when an email is sent. So, try waiting one or two days. Then the server might be back up when you send the email again a few days later.

3. Is the Email IP Blacklisted?

  1. It might be the case that an anti-spam filter has blocked the server IP/domain for the email server when error 550 arises. To check if that is the case, open the MX Lookup page.MX Lookup email error 550
  2. Enter your email domain in the text box, and click he MX Lookup button. That will then provide IP address details for the email domain entered.
  3. Copy the IP address for your email domain to the clipboard by selecting it and pressing Ctrl + C.
  4. Then open the blacklist check page in a browser.Blacklists utility email error 550
  5. Paste the IP address into the text box with the Ctrl + V hotkey.
  6. Click the Blacklist Check button, which will show users a list of email blacklists.

If the blacklist check highlights that an anti-spam filter has blacklisted the email IP address entered, that’s why you can’t send the messages. Try sending the message with an alternative email address if you can. Alternatively, users who don’t have alternative email can set up new webmail accounts at Yahoo, Gmail, etc.

4. Enable SMTP Authentication

  1. Some uses might need to enable SMTP authentication for their email client software. Outlook 2013/16 users can do that by clicking Tools in the Outlook window.
  2. Select Account Settings on the menu.
  3. Then select an email account, and click the Change button.
  4. Press the More settings button on the Change E-mail Settings window that opens.
  5. Select the Outgoing Server tab on the Internet E-Mail Settings window that opens.Internet E-mail Settings window email error 550
  6. Select the My outgoing server (SMTP) requires authentication check box.
  7. In addition, click the Use same settings as my incoming mail server radio button.
  8. Click the OK button.
  9. Mozilla Thunderbird users can set up SMTP authentication by clicking Tools and Account Settings in Thunderbird’s window.
  10. Select Outgoing Server on the left of the window.
  11. Select an email server, and press the Edit button to open the window shown directly below.Mozilla Thunderbird's Settings window email error 550
  12. Then users will need to enter the SMTP settings for their email server. For example, Gmail users will need to enter ‘’ as the server address and ‘587’ or ‘465’ as the TLS/SSL port numbers.
  13. Click the OK button after entering the required details.

Those resolutions might fix email error 500 for some users. However, the intended email recipients might also be able to fix the issue by turning off their antivirus software firewalls or emptying their inboxes. So, some users might need to get in touch with the recipients (without emailing) to fix the issue.


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