Two days ago I began getting the following two messages from Thunderbird when trying to get mail: "The current operation on 'Inbox' did not succeed. The mail server for account [name] responded: User is authenticated but not connected" and "Server outlook.office365.com has disconnected. The server may have gone down or there may be a network problem." The problem occurs on two Windows 10 PCs, but I am able to get mail on my iPad and iPhone, as well as through the office365 webmail. The server is definitely not down: emails are reaching my accounts, but they are not getting through Thunderbird. I am able to send emails from the PCs through Thunderbird and they are received. However, the emails that I write do not go into the 'Sent' folder and I get the same error message with 'Sent' replacing 'Inbox'. I spoke at length with my email hosting service, and they are investigating, but did tell me they had encountered the problem with other people who were using Thunderbird as their email client. So I am asking if you have any suggestions. As a business, we depend on email. Many thanks.