When you use MSGTAG the email goes through the MSGTAG desktop application on its way to your usual SMTP server (typically provided by your ISP). The MSGTAG desktop application acts as an SMTP proxy, passing the email on unchanged except for the addition of an HTML image reference. The image reference includes a unique ID. When the email is received, the recipient’s email client sees the image reference and requests the image from the MSGTAG web server so that it can be displayed in the email. Usually the image is invisible because it is only 1 x 1 pixel in size.
The MSGTAG web server sends back a standard image and makes a note of the unique ID and the time that it was requested. The server then associates that ID with a specific user and email. It then sends the user a receipt notification email.
I don’t like it. How do I make sure no one MSGTAGs me?
We’re aware that not all Internet users wish to receive MSGTAG tagged emails. That’s why we implemented the contact settings in MSGTAG Status which allow the user to automatically disable tagging for certain recipients who have asked not to be tagged.
- a text-only mail client (hardly anybody uses these)
- a mail client that enables the user to block external HTML images (these are becoming more popular as a countermeasure to spammers using 1×1 images to verify email addresses)
- a firewall that stops the email client from requesting the MSGTAG image from the MSGTAG web server
- a spam filter like Mailwasher that enables the recipient to preview the message on their mail server without downloading it into their HTML mail client. N.B. Mailwasher is a product of Firetrust, a client of eCOSM, who developed MSGTAG for Fisher Young Group. In case you’re wondering, Mailwasher came first and this shouldn’t be construed as ’selling both the disease and the cure’.
Whilst researching MsgTag and how to block it I found the following forum very useful:
http://www.mickeytheman.com/forums/index.php?s=df87bf6f4cb189f06f1c040f83f15810&showtopic=620&st=0&#entry2198
In summary you can either redirect img.msgtag.com to 127.0.0.1 or use your firewall to block all outgoing traffic to that web address.
The advantage of this is that you don’t have to block all external HTML images.
Hope this is of use.
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