Adding alternate mail id from Microsoft Graph API - microsoft-graph-api

Question

I am trying to add an alternate email with Microsoft Graph API from a.Net Core app.
The user class in Microsoft Graph does not provide a property for adding an additional mail id.

Answer 1

You can using Azure AD Graph to add the mail id to the otherMails. Here is sample to update the this property:
PATCH: https://graph.windows.net/{tenant}/me?api-version=1.6
authorization: bearer {access_token}
{
"otherMails":["test#test.com"]
}
Refer the links below for the user entity and update user REST:
Entity and complex type reference | Graph API reference
Update User

Answer 2

Here is the C# code to retrieve the alternate email
Select(u => new {
u.DisplayName,
u.Mail,
u.UserPrincipalName,
u.OtherMails
})
.GetAsync();

Answer 3

You can get the alternate email from the "otherMails" property on a User in the Graph API Docs.
Note that this is only returned on a Select, so you need to include the query parameter "$select=otherMails" to see it.
GET https://graph.microsoft.com/v1.0/users/USER_ID?$select=otherMails
authorization: bearer {access_token}
{
"#odata.context": "https://graph.microsoft.com/v1.0/$metadata#users(otherMails)",
"#odata.id": "https://graph.microsoft.com/v2/YOUR_AAD_TENANT/directoryObjects/USER_ID/Microsoft.DirectoryServices.User",
"otherMails": [
"altEmail#website.com"
]
}