Email error 550 can arise in various email client software, such as Outlook and Mozilla Thunderbird. The error arises when some users send emails with client software.

  • The email error 550 can happen with any client or account but it’s directly linked to the SMTP.This problem occurs when the outgoing server hasn’t sent the email signaling that the recipient’s mailbox isn’t available.There are lots of possible causes for this issue, including entering the wrong email address or malware infection.

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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.

What causes the email error 550?

That can be due to a few things, and in some cases, it might actually be an issue that the intended recipient, not the sender, can fix.

It may be that your email client is not configured properly or a more zealous firewall blocks it. However, the most simple cause for this error is that you entered the wrong email address.

This problem may also occur if the recipient cannot receive your email for some reason or he blocked your domain.

How can I fix the 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, strange characters, or spaces in the email address before clicking the send button.

Although not likely, the recipient’s server might be down when an email is sent. So, try waiting a few minutes or hours, then try sending the email again.

2. Is the Email IP Blacklisted?

  • 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.
  • 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.
  • You will see the list of hostnames and IP addresses for the webmail servers so you can just hit the Blacklist Check option for each of them to verify if it’s blocked by anyone.
  • You can also open the blacklist check page dirrectly and paste the IP address into the text box, then hit 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.

In case you don’t have another email address, set up a new webmail account at Yahoo, Gmail, etc. in just a couple of minutes.

3. Enable SMTP authentication

  • If you’re using Outlook, first click on the File button.
  • Now select your account from the top if you have multiple ones, click on Account Settings, and select Server Settings from the menu.
  • Click on Outgoing email, select the My outgoing server (SMTP) requires authentication check box and make sure that the Use same settings as my incoming mail server option is also checked, then hit Next.
  • Mozilla Thunderbird users can set up SMTP authentication by clicking Tools and Account Settings.
  • Select Outgoing Server on the left of the window.
  • Up next, select an email server, and press the Edit button to open the window that you can see below:
  • Then you will need to enter the SMTP settings for your email server. For example, if you have a Gmail account enter smtp.gmail.com as the server address and 587 or 465 as the TLS/SSL port numbers.
  • Click the OK button after entering the required details.

How can I prevent the email error 550?

Although this occurrence is not pretty predictable and it’s hard to pinpoint its exact cause, there are some things you can do to prevent this from happening.

➡ Use anti-spam filters

One cause for this problem might be that your email client is infected and it sends out spam messages to all your contacts.

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Using anti-spam filters from a strong antivirus can save you from this ever happening. In fact, it will improve the overall security of your PC and data so it’s a good idea any way you put it.

➡ Change the email sending frequency

Sending too many emails in a short timespan can make servers believe you’re a spammer trying to clog the network and that will also get your email blocked.

So if you’re sending more than 50 emails an hour, slow down a little bit and you won’t get in any trouble.

➡ Change your password frequently

The spammer scenario happens because you probably have a weaker password that got highjacked by wrongdoers.

Changing your password often and selecting a more complicated key will solve this problem and prevent any such problems.

Those resolutions will fix the email error 500. 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, if your email is blocked by the recipient side, the only solution is to contact the person using another communication method to fix the issue.

If you can’t make your email client work, you may also consider the best email clients for Windows and pick a better solution.

For any suggestions or other solutions we might have overlooked, write us a line in the comments section and we will get back to you.

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