Migrating Exchange Web Services (EWS) Directory and Recipient resolution code to the Microsoft Graph
One of the more complex things to migrate in EWS when migrating to the Graph API is any directory access code that uses one of the following EWS operations FindPeople ResolveName ExpandGroup (ExpandDL) or if your using OnPrem you maybe using System.DirectoryServices to do direct LDAP requests of Active Directory. With the Microsoft Graph API these Directory based mail operations don't exist, because you have full access to the underlying AzureAD, so in theory everything should be achievable without these type of operations. For the most part this is correct where is starts to get a little grayer is around this like Address Lists and Exchange recipient types mostly because the Graph doesn't expose the following underlying Active Directory properties msExchRecipientDisplayType msExchRecipientTypeDetails msExchRemoteRecipientType so this can be a limitation if your migrating from LDAP code and some FindPeople implementations if your searching based on AddressList. Microsoft Graph