Find a User by Email Address

Since it is a odata, you can query using odata syntax. Odata syntax here

var queryString = HttpUtility.ParseQueryString(string.Empty);
queryString["api-version"] = "1.6";
queryString["$filter"] = "signInNames/any(x:x/value eq '[email protected]')";

string url = "https://graph.windows.net/" + tenant + "/users"+ "?" + queryString;

$filter did the trick

queryString["$filter"] = "signInNames/any(x:x/value eq '[email protected]')";

Take a look at the B2C.exe implementation, first get that working: https://azure.microsoft.com/nl-nl/documentation/articles/active-directory-b2c-devquickstarts-graph-dotnet/

You will notice that the user is referenced by GUID or by UPN, not by email! Emails are in the collection signInNames

To query on email address, you will need to specify a filter: https://msdn.microsoft.com/en-us/library/azure/ad/graph/api/users-operations#GetUsers

Start with the GetUsers(to get all users), then update password and last the filter.

signInNames isn't the only place that emails are stored. It could also be userPrincipalName or otherMails. You'll want to use the following query to search all possible fields for an email.

/users?api-version=1.6&$filter=otherMails/any(x:x eq '{email}') or userPrincipalName eq '{email}' or signInNames/any(x:x/value eq '{email}')