I use Windows 10, Firefox, Thunderbird. My ISP is Suddenlink Communications. You need to know that I'm a retired Presbyterian pastor and not much of a geek. I suspect my email problems began when Thunderbird Version 78 was replaced by Thunderbird Version 91 about 3 or 4 weeks ago. I have spoken to Suddenlink technical support techs 3 or 4 times. Today I spoke to tech who had me log onto Suddenlink.net using Chrome. My Thunderbird email worked perfectly using Chrome. The test I tried was to email myself to see if Chrome could deliver my email msg question.....Is this cussed Thunderbird Email ever going to work correctly?......about 10 seconds later my sent email arrived at my Inbox on Chrome. The tech's conclusion and mine was that the Thunderbird server, Suddenlink's server, and my desktop computer are NOT in sync. How my email can work correctly using Chrome is a mystery to me because I have NOT installed Thunderbird on my Chrome browser. If you need me to help your tech in some way it would be best if you call me at [removed phone# from public] first and if I'm not in please leave a message on my answerphone. This is the bottom line. If somebody doesn't correct this out-of-sync email problem for I will be writing the CEO or whoever is in charge. I have been a customer of Suddenlink since 2009, a user of Firefox since 2007 and a Thunderbird user for over 5 years, I think. Furthermore, I don't like Microsoft or Google but if I have to switch and deal with the demons of the devil, I will.....to get my email back and operating correctly. Cordially, Jon L. White, Pastor