Firstly, Exchange *protocol* is not the same as Exchange *server* or Exchange *account*.
The Microsoft Exchange Web Services (EWS) protocol [is being phased out](https://techcommunity.microsoft.com/t5/Exchange-Team-Blog/Upcoming-changes-to-Exchange-Web-Services-EWS-API-for-Office-365/ba-p/608055).
Microsoft stopped updating the EWS libraries [in 2016](https://github.com/OfficeDev/ews-java-api).
So, it makes little sense to add this protocol anymore.
You can use a Microsoft Exchange account if it is accessible via IMAP, which is mostly the case.
You can use a Microsoft Exchange account if it is accessible via IMAP, which is almost always the case because all Exchange servers support the standard IMAP protocol.
See [here](https://support.office.com/en-us/article/what-is-a-microsoft-exchange-account-47f000aa-c2bf-48ac-9bc2-83e5c6036793) for more information.
Note that the desciption of FairEmail starts with the remark