Not sure where FF is part of this? But, as I saId, you right click the
message, in the inbox, and you should see the option.
The option to add sender to contacts list would be greyed out, of course, if the contact is already there, as you state.
fwiw. You might find it beneficial to cicik the icon with the small square with the white arrow (over on the right of the top bar), and select "Show menu bar", if you have not already done so.
Add contact, as Cliff says, is sitting right along side the senders name, again in the inbox
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