In March 2018 Microsoft published an announcement advising that basic authentication to Exchange Web Services (EWS) for Exchange online will be retired on October-13 2020. Please see the below link for the original announcement from Microsoft.
Office365 administrators can also view details of the announcement in the O365 Message Centre by searching communication numbers MC191153 and MC204828.
How does this affect ResourceXpress?
ResourceXpress is a .NET application which utilises Exchange Web Services (EWS) to synchronise and display resource bookings on our range of products. When basic authentication is retired any site that still uses this method will immediately see a disruption to ResourceXpress functionality.