I am trying to follow all of this, I have a tenant that has 650 active users. We have folks using a variety of clients and different versions to things from older outlooks, iOS, Mac Mail, thunderbird, etc. Some support oauth2 and some don't.
I only became aware of this looming change about two weeks ago, since then I have had an open ticket with support trying to understand it and get more details. I have been pushing for specifics but am finding more on my own. The partner I purchase the licenses from has had very limited responses as well, there was a call today about this both with the partner and I had one as well with I think the third team lead. Ironically MS support today told me to contact Apple for help, that well didn't really go well. It seems like the frontline folks at both companies are not armed with the information needed, I keep getting told by MS support they will get back to me once they escalate and get mroe details.
As I understand it imap/pop3 will require oauth2 starting 10/1/2022. I have followed the steps shown in the blog article, upgraded my iOS devices to 15.6.1 to get an idea of what users will see, how can I tell what users have been moved so to speak already so we can narrow down the list of users to touch. Is there a power shell command or some way to get a unique list. This of course assumes I have followed the steps correctly. Any direction appreciated.