Exceptions are only honored if you use "Clear history when Firefox closes", in all others case all cookies you select are cleared. Exceptions are part of the "Site settings", you lose the exceptions if you clear the site settings.

Thanks for answering one of my questions. Still wonder about the other one. Is there some easy way to do it and, if not, can it be added?

There is a Cookies policy to specify for which origins to allow or block cookies.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-policiesjson
• https://mozilla.github.io/policy-templates/#cookies

There are some examples further down.

Thanks for another reply. So, using policies.json involves listing the exceptions in a file, so the file can be easily changed and more importantly backed up so the exceptions can be recovered if inadvertently deleted/lost?

For Windows, it says to create a directory called distribution where the EXE is located and place the file there. Does this mean in the folder where firefox.exe is located?

Yes, that is the Firefox (binary) installation folder as listed in "Help -> More Troubleshooting Information" (about:support).

Thanks a lot. Your information will allow me to make better use of the site exceptions for cookies. Consider it solved, even though I still wish it could be done within the GUI.