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Error message ‘550 the content of this message looked like spam’

Sometimes you get an error message  when sending mail. The error message '550 the content of this message looked like spam' indicates that the sent message cannot be delivered. In this article, we will explain why you are getting this error message and how to resolve it.

The reason you get this message is because the email cannot be delivered and the incoming server has a spam filter that classifies the email as SPAM. And this does not happen without reason.

At the incoming mail server, all e-mails are viewed and rated by the spam filter. Each mail gets points, the more points the more likely it is to be rated as spam. The points are awarded by a certain algorithm, it looks at, for example:

  • Is the sent mail server blacklisted?
  • Does the name of the mail server match the name of the sender?
  • Does the content of the e-mail contain potentially harmful content or does the attachment contain potentially malware?
  • Does the content of the e-mail contain certain words that indicate spam or links to blacklisted (phishing) sites?

The algorithm used is very precise and based on millions of other mails already processed.

If the point score of a message exceeds a certain threshold, the message is classified SPAM. To inform the sender, the sender receives the so-called 550 error message. The sender then knows that his mail could not be delivered.

If this happens to you, you should check your mail and a number of settings.

Check SMTP server settings

The SMTP server is the server that sends your mail, which you set up separately in your mail programme. The settings include the option "This server requires authentication" (or something similar). In many cases, the SMTP server also requires this so you have to tick it.

Check the content of your message

Check your e-mail message to make sure it does not contain any 'wrong' words or links to blacklisted sites.
If you send an attachment that may contain blacklisted text or links, and you cannot send it by e-mail  please use, for example, WeTransfer (or another service)  to send the attachment anyway.

Still an error message?

If you keep getting an error message and can't figure it out,  please contact whoever arranges the web hosting and include the original message headers of your mail. Based on this, a solution can be found.