Spammers use backscatter to clog your mail queue and harm your email reputation. They do this by sending emails to invalid addresses at your domain. When the Exchange Server processes these emails, it generates and sends a Non-Delivery Report (NDR) back to the sender. However, once the NDR reaches them, they report it as spam, which negatively impacts your domain. In this article, you will learn how to fix spam messages in the Exchange Server queue viewer.
What is happening?
The Exchange Server is open to all incoming and outgoing messages from the internet, which makes it easy for spammers to send unwanted emails directly to your system. This is happening because the SMTP port is open to the public, letting spam flow right through without any filter in place.
The good thing is that we have not set a send connector, and we did this for demonstration purposes. Now, if you have a send connector, it will send these email messages to the recipients.
- Start the Exchange Toolbox
- Click on Queue Viewer
- Double-click on the hop domain that contains many messages count


- Double-click on a message


- Verify that the message is spam


Fix spam messages in Exchange Server
To solve this, you need to ensure that only your spam filter has direct access to your Exchange Server. This means you should only open the port between your spam filter and Exchange Server. Once you’ve done this, all incoming and outgoing messages will pass through the spam filter first, where spam can be blocked.
Here’s what you need to do:
- Close unnecessary open ports on your Exchange Server to restrict access.
- Open the port only between your spam filter and the Exchange Server.
- Ensure all mail traffic (incoming and outgoing) is filtered through the spam filter before reaching your Exchange Server.
- Use a proper spam filter to prevent backscatter. A good spam filter can identify and stop the bounce-back messages that contribute to backscatter.
Recommended Spam Filter
To ensure your email traffic is properly filtered for outgoing/incoming filtering, and backscatter is blocked, consider using a trusted spam filter service like SpamBull. This will help block spam and ensure only legitimate messages reach your Exchange Server.
Remove spam messages in queue viewer
Once you have set up the spam filter, remove the spam messages in the Exchange Server queue viewer:
- Start the Exchange Toolbox
- Click on Queue Viewer
- Double-click on the hop domain that contains many messages count
- Select all the spam messages
- Click on Remove (without sending NDR)


- Select Expand the scope of this action to include all items in this filter
- Click OK


- Click Yes


- All the spam messages are successfully removed and NDRs are not sent


That’s it!
Read more: Protect domain from spam, phishers and viruses »
Conclusion
You learned why spam messages appear in the Exchange Server queue viewer. It’s crucial to use a spam filter to prevent unwanted messages and backscatter from clogging up your mail queue. The key is to allow traffic only between your spam filter and Exchange Server. Once this is set up, you can have peace of mind knowing that all your emails are properly filtered.
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