Use the contact info here : https://support.mozilla.org/en-US/kb/forum-response-firefox-sync-verification-email-faq

Please let us know if this solved your issue or if need further assistance.

Thanks for the link but this is about iCloud Bookmark sync (syncing Safari Bookmarks between iPhone and Firefox running on Windows 7), not Firefox Bookmark sync.

This feature worked prior to Firefox v57.x. The feature requires the user to have an iCloud account with Bookmarks activated, iCloud software running on Windows and the iCloud Bookmarks extensions added to Firefox.

Aprpeciate your interest and your response ......

Then please go here : https://support.mozilla.org/en-US/questions

Apple created that iCloud extension for Firefox and they support it over here. https://support.apple.com/country-selector/icloud

US support part is here: https://support.apple.com/icloud

Appreciate your response but this link is not helpful with respect to solving the problem.

they support it