Nice to see, but unfortunately it's not uncommon for orgs using Outlook/Office to disable Exchange client support and require use of the official clients. It's highly unlikely and maybe not even possible, but I'd like to see desktop and mobile mail clients implement some kind of workaround.
Microsoft plays wack a mole with 3rd party clients trying to gain access when it's been disabled so it's thankless job for their developers. Not to mention, if I'm disabling your third party access, trying to circumvent is Employee policy violation and you get to talk to HR about why you don't want to play by the rules.
If you want your employees to install malware, maybe you should issue them a company device instead of requiring them to install it on their personal device.