I have just installed Thunderbird and connected it to my Outlook356 account in IMAP mode. I see emails and folders, no problems. However in the initial setup, it did not discover my calendar and I have not been able to get Thunderbird to connect to it manually. I go to Create New Calendar, click On the Network, put in my username (my outlook email address) and use outlook.office365.com as the location, with Offline Support ticked. When I click Find Calendars it asks for my password for outlook.office365.com, which I enter, then it comes back with "The credentials you have entered were not accepted. Please check your settings.". I know the password is correct. It is the same one I used to get the emails side of things working. I have also been able to successfully connect Bluemail to my outlook365 account and have both emails and calendar working in it - it's just not as rich an environment as Thunderbird, which I would prefer to use (I'm fed up with the Outlook client and want to get off it!). Any clues on what I might do to resolve this calendar connection issue? Thanks, Nick.