Hi, I have thunderbird connected to a number of client corporate Office 365 systems (5 in total). The teams option works fine for 4 of them and is quite usable for chat but one of them responds that the browser is an unsupported version. I use Ubuntu 24.04 and have thunderbird and firefox installed from deb files (and the repos) so both are the current/release versions and overall everything works well so I don't believe there is a systemic issue. All connections to the clients' exchange systems are through the owl plugin. With the one client, as soon as you try to connect to their teams site, the 'Hmmm, your browser isn't supported' page comes up. As I manage that client's office platform, I know I've not made any changes to the back-end settings nor have I done so or had to do so on any of my other clients platforms so I don't think there is anything unusual about the Office 365 side (but am willing to be proved wrong). If I try logging in to the problematic teams site using firefox it works perfectly so I don't believe it is firefox being an issue. I have deleted and re-added the account. Has anyone else seen this and got it sorted, and if so how please? Many thanks, Scott...