Upcoming changes to Office365
So...what's going on?
The University has decided that the current method of logging into Office365 using only your Active Directory (AD) username and password is no longer secure enough. As such they will be implementing new security requirements for e-mail clients (ie: the e-mail program installed on your computer/tablet/smartphone) that will go into effect on March 1, 2022.
What changes are University IT implementing?
All e-mail clients will be required to support both an O365-specific protocol for logging in called "OAUth2" and also must have built-in support for Duo 2-factor authentication. Not all e-mail clients support these.
Is that all?
Unfortunately, no.
I've also been informed that on October 1, 2022 Microsoft will stop supporting the use of the industry-standard e-mail protocols for checking/sending e-mail (ie: IMAP, POP, and SMTP) and will only support the use of Microsoft-specific protocols (commonly referred to as "Exchange format") with Office365. This will also render some mail clients wholly incompatible with Office365.
The combination of the security changes being implemented by University IT and the service changes being implemented by Microsoft will require all of us to soon make changes to how we interact with Office365 to ensure continued compatibility with Office365 over the years to come.
Is my current e-mail client compatible with these new requirements?
Per University IT, the e-mail clients that they will officially support are as follows:
Microsoft Windows: Microsoft Outlook
Macintosh computers: Apple Mail or Microsoft Outlook
Linux: Mozilla Thunderbird (with a PAID add-on called "OWL" that adds the needed OAuth2 support)
Apple iDevices: Apple Mail or Microsoft Outlook
Android devices: Microsoft Outlook
All of these mail clients support OAuth2, the use of Duo, and can be configured for "Exchange format".
This does NOT mean that other mail clients won't work (for example, Thunderbird on a Mac or the Evolution mail client for Linux can both be made to work), but the clients listed above are what they will be officially supporting.
What about the webmail system (OWA)?
As far as I know none of these changes will have any affect on the OWA webmail interface. These changes are limited to mail clients installed on your computing devices.
What if I'm already using one of the mail clients listed above?
Already being a user of one of the "supported" e-mail clients is a big plus, but it doesn't automatically mean you won't have to reconfigure your mail client(s) to make them compliant with the new security restrictions. University IT will be releasing detailed instructions soon for (re)configuring mail clients...a link to those will be added to this wiki when they're made available.
So...what do I need to do?
The first thing you need to do is NOT PANIC! 
While e-mail can be a pretty complicated it's not an insurmountable problem and you have resources (including myself and University IT) to help you with this.
My first suggestion is for you to make sure the Duo account associated with your River Campus AD account (called "UR Active Directory" in Duo) is enabled. The Duo account used for making VPN connections to the university (called "University IT NetID" in Duo) is NOT the correct version of Duo for O365. Here's a link for enabling the AD-version of Duo on your smartphone or tablet (the process requires you to be connected to the UR network):
https://tech.rochester.edu/enroll-in-duo/
The next thing I suggest you do is perhaps take inventory of how you currently interact with O365 (ie: what mail clients you currently use and what devices you use them on) and use this as an opportunity to make some beneficial changes. Perhaps standardizing on the same mail client for all of your devices, or even changing which devices you do and don't use with O365 will simply your life and improve your workflow.
Once you have an idea of how you'd like to move forward, consult the documentation provided by University IT regarding how to implement the needed changes.