Something is very wrong with your exceptions! You may want to remove those.

You cannot use an asterisk or other wildcard when setting Firefox permissions. Can you paste one of the following and then click Allow, and then repeat with the other one:

• Consumer site: https://outlook.live.com
• Office 365: https://outlook.office.com

(See screenshot for how that should end up)

Does that help?

I should ask what your general cookie setting is, since this assumes you allow session cookies for other sites and only need exceptions for the special cases. If you block cookies for all sites, you'll almost certainly need more exceptions to stay logged in on the Office365 infrastructure.

"Something is very wrong with your exceptions! You may want to remove those."

Yes! That is what appears when I attempt to add the URLs that are requested by MS.

"Exceptions - Cookies and Site Data" will not allow me to store URLs. I get the nonsense in the first picture instead.

If you paste

https://outlook.office.com

does Firefox let you click Allow?

But anyway, if you are not blocking cookies, then I don't think any exceptions should be required.

(Bear in mind that "Trusted Sites" is an Internet Explorer list not a Firefox list, so the instructions appear not to be tailored to Firefox.)

Maybe there is a different source of the issue, but I'd just be guessing.

Did you already try flushing the cache in case Firefox is using any old files that are obsolete? More info: How to clear the Firefox cache.

Can you modify cookie allow exceptions via "Tools -> Page Info -> Permissions" ?

• https://support.mozilla.org/en-US/kb/page-info-window-view-technical-details-about-page

Apparently the wildcard (*) was the issue. By using these URLs as exceptions, without the wildcards, the URLs were accepted and Outlook Web works fine now. Thank you for taking time to discuss this issue with me.