you option for remote content are explained here. https://support.mozilla.org/en-US/kb/remote-content-in-messages

Note particularly the information under "Display remote content by default" where blocking is discussed.

Well, that doesn't solve the issue. I have a remote content website listed as blocked on the Preferences/Privacy/Mail Content settings option. An ad from that website just now was displayed in the email.

It looks like Options is now Preferences. There is no Options item in the drop downs.

ok what is the link you have in preferences. Copy it. What is the link in the email? You might want to copy that as well.

I really doubt they are the same. Or your blocking a specific image, not the site.

OK, here's what I've figured out. The reason the block on the URL doesn't work is because it is not a link to content of any sort. It is a link to a second party URL which then links to the URL that is the actual source for the ad content.

Here is link in the email for one of the ads. http://sli.dilbert.com/click?s=255507&li={LIST_ID}&e=myemailaddress&p=20220403

What I put into the Exceptions list is http://sli.dilbert.com, which looks to me to be the usual type of entry in the Exceptions list.

The other ad I'd like to block has this URL. CAUTION - this link leads to an Amazon ad for sexual enhancement products which is why I want to block it. https://sli.arcamax.com/click?s=25301&li=comics641&m=37c9c40479b32ad69d9ef3b480b61fd8&p=202204032101041&stpe=default

When I truncate the two sli URLs and enter them into Firefox I end up at https://p.liadm.com/............. Obviously the sli URL leads to a gateway that then goes to the ad provider, Amazon for the sex product and outdoorvoices.com for the Dilbert link.

As I see it, what is needed in Thunderbird is code that follows the links to the actual ad content source and then blocks that content.

Below each of the ad is a link labeled LiveIntent that goes to https://www.liveintent.com Ad Choices page.