Document information

Document ID: 4661
Subject: User tracking filter
Creation date: 12/14/15 4:35 PM
Last modified on: 8/13/18 4:08 PM

User tracking filter


Some of the emails getting blocked have the following reason:

Email is referring to, which contains user tracking information.


Consider the following raw source code of a sample email.

Subject: Re: Your message
From: Greg Brown <>
Date: Tue, 29 May 2012 09:05:33 -0400
Content-type: text/html; CHARSET=US-ASCII


<img src="">Hello</a>


This sample message contains a URL that has the user's email address. The sender will know if the recipient clicks the link, which serves as an acknowledgment and a validation of the email address. This mechanism is used by many spammers to find out if their spamming campaign is a success.

The URL User detector custom rule detects such messages and assigns a score. If you have messages going in the wrong category, try adjusting the score for this filter. Click Filter Management > Content Filters > Custom Filters to access this filter.

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