Email-window: Image source in placeholder (when image loading blocked)

Hi folks,

when I am looking through my newsletters, I see many emails with suppressed image loading and so seeing placeholders (marked green).

I could go into the preferences (german on my screenshot: “Einstellungen”, marked red) and allow some sources. But currently, that is always gambling.

After I opened the preferences in the email-window, I see several sources, I could allow (see second screenshot). Obviously some are real image sources, some I suspect to be cdn’s of email senders and trackers.

What I want:
I only want to allow the real image-sources. So it would be good, to see the image-sources on the placeholders. Maybe, the best way would be to show the full path on hovering the placeholders.

Is there a addon already available, doing what I want? Or would that be a good feature for Thunderbird itself?

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