I am unable to receive or send external emails from a number of ISP's. Appears to have been since an upgrade to 78.5.0. Others I know have the same problem. Message says connected to server, but no new emails are coming in, I can't move emails to other folders, and sending emails results in sent copies not going to the sent folder, but instead a message offering saving the Local Folders is presented. It isn't a server problem because I can use Outlook as normal - but I detest Outlook, and would prefer that Thunderbird worked!