SMTP 550 Blocked - Why is my email blocked with an error message?

EQ Admin

EQ Forum Admin
Staff member

Is the email that you are sending bouncing back with one of the following errors?

  • 550 Blocked
  • Too much spam
  • Poor reputation
  • Blocked by Email Reputation Service
In addition to traditional blacklist checks, it's also a good idea to monitor your sender score.

Your sender score is your email report card.

Many large email providers will take action on your email based on your sender score.

Similar reputation services are offered by other companies including Cloudmark, Trusted Source, Trend Micro, Proof Point, and Microsoft.

This is an example of a good sender score:

Sender Score - Very High Volume - Good Sender.JPG

As you can see it's possible to be a very high volume sender and still have a good email reputation.

This is an example of a bad sender score:

Sender Score - Very High Volume - Bad Sender.JPG

There are many reasons why an IP address might have a bad sender score including:

  • They are a spammer (intentionally or unintentionally)
  • They have compromised email accounts sending spam
  • They have a compromised web site sending spam
  • They have a computer infected with a virus / spyware / malware
  • They are an open relay
To improve your sender score, find and fix the source of the email abuse, and if you are a good sender your score will increase over time.