azure https://graph.microsoft.com/v1.0/users/ code example

Example: get ad user using email address microsoft graph C#

// Retrieve a user by id
var user  = await graphClient
    .Users["00000000-0000-0000-0000-000000000000"]
    .Request()
    .GetAsync();

// Retrieve a user by userPrincipalName
var user  = await graphClient
    .Users["[email protected]"]
    .Request()
    .GetAsync();