MacroView DMF and Message 8.5 and later versions support Modern Authentication and install with this feature enabled by default.
What is Modern Authentication?
Modern authentication brings Active Directory Authentication Library (ADAL)-based sign-in to Office client application enabling sign-in features such as Multi-Factor Authentication (MFA), SAML-based third-party Identity Providers with Office client applications, smart card and certificate-based authentication, and it removes the need for Outlook to use the basic authentication protocol.
Enabling or disabling Modern Authentication
When Modern Authentication is enabled in MacroView DMF and Message you will not be prompted to authenticate to SharePoint Online each time you start Outlook, DMF Explorer or use the Open and Save to SharePoint options in other Office applications. Once you have authenticated will only be ask to re-authenticate if you change your password, sign out or do not use DMF or Message for long periods of time.
To enable Modern Authentication set the below registry value to 1 (default) or to disable it set the value to 0.
What is different when Modern Authentication is enabled?
When Modern Authentication enabled right clicking the SharePoint Online tenant node in the Tree View will show who you are currently signed in as and allow you to sign-in with a another account.
The current signed in user and an option to sign in as a different user is also available in the top right corner of the server dialog under DMF options.
When you select a library or other location on SharePoint Online (Office 365) for which you do not have access, or you are not currently signed into, the top of the file list will show a gold bar warning message with an option to sign in.
More than one SharePoint Online (Office 365) tenant?
If you have multiple SharePoint Online (Office 365) tenancies that are licensed to use MacroView DMF or Message, you can access all of them in the same DMF session if Modern Authentication has been enabled. With Modern Authentication disabled you can access only a single SharePoint Online (Office 365) tenancy.
For more information see Working with multiple SharePoint Online tenancies.