emails opened using thunderbird wont trigger my opened email function

Question

I am using an image attached to an email to trigger an opened email function. it works fine in all email accounts but it does not work when opened using thunderbird or could also not work if using outlook(have not yet tried). could it be that thunderbird purposely prevented such thing from happening? since there is no full proof of creating such function how would i go around thunderbird on this problem?

The email will contain this image: http://site/admin/tracking.php?uid=2&msgid=0&sched=2

Answer 1

By default, Thunderbird and other email clients disable images automatically until the user clicks "show remote content", and unfortunately there's no way to get around this behavior; you can however ask subscribers to add you to their address book so that images in your emails are already turned on. This is actually the only thing you can do against the image blocking.