Microsoft Intune is a MDM system to make syncing data with mobile phones secure and compliant. Due to the way Nylas syncs mail with Microsoft accounts it's possible that some of your customers might have trouble logging in initially if their organization has Intune or another MDM system in place (this includes self-hosted Exchange servers as well as Microsoft's Office 365 cloud offering).
For the most part, we do support mail servers that have MDM systems in place, though it may require some extra setup. Nylas Support is here to help - let us know and we can work with you and your customer's IT admin to get things setup and running smoothly.
Your user might get an automated email from Microsoft Intune if they try to authenticate through Nylas and Intune hasn't been properly configured.
The best way we've found to get an organization using Intune working with Nylas is to enable the Exchange connector. Please see Microsoft's guide on how to first connect Intune to Exchange Online with a service to service connector.
After Intune is connected properly to Exchange you should follow our Suggested Office 365 Settings guide to verify that all of the Exchange settings are correct.