After reading the information you provided in the links, I understand how it works now. If I click the button, it will do a one time connection to the internet and display all the remote content. There is no undo option for this, it just happens. However, nothing is stored in Thunderbird for this action, which is why it will ask me that every time, even if I click the button. Its more like a warning (do you want to see this content), and by clicking the button, I accept the risks.
If however, I want to always accept content from a trusted source, I then click the link "always load remote content from ....", it will allow me to add that specific e-mail to my address book. I did see the suggestion in one of the links to create another address book (outside of the personal one) to keep these separate, and easy to manage. When I do this, the check box "Allow remote content" is checked by default (as indicated by the red arrow in my picture) so that when I do receive and e-mail from this address, any remote content will automatically be displayed.
Again, thanks for the links and helping me understand this functionally of Thunderbird!
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