Hi there,
I designed and specified a small software product, hiring third party Microsoft developers to build it . The software, developed using .Net framework, makes extensive use of the data held on MS Exchange Server, accessing it via EWS. I have sold the software to my first customer, but we are stuck because the customer is unable to progress beyond the login screen getting 'user not found' whatever we try in order to log in. I have hired a 'heavy hitter' in an attempt to resolve the problem (which we originally suspected was to do with SSL. However, having run a battery of tests he has concluded: 'If the tests at the Microsoft site are now all passing [which they are], that would kind of rule out an issue with Exchange. It would then be something that the application is doing that works fine on later versions of Exchange.'
The area under suspicion now is around MS Exchange Server versions. The software company developed the product against MS Exchange Server 2013 whereas my customer is running MS Exchange Server 2010. I have found a statement on Microsoft Docs (see section about EWS-operations0in-exchange) that says work against Exchange versions is forward compatible: 'The versioned schemas are implemented so that clients that are designed against an older version of EWS will work with a newer version of EWS.' However, I have not been able to find a statement confirming the reverse i.e. that clients designed to work with a newer version of EWS will be able to work with an older version. NB all software is on-premise - not Office 365.
Is anyone there able to confirm the position for us please?
Regards
William