string scope = _configuration["AzureAd:Scope"];
string[] scopes = { scope };
var tenantId = _configuration["AzureAd:TenantId"];
var clientId = _configuration["AzureAd:ClientId"];
var clientSecret = _configuration["AzureAd:ClientSecret"];
var options = new TokenCredentialOptions
{
      AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
};
var clientSecretCredential = new ClientSecretCredential(tenantId, clientId, clientSecret, options);
var graphClient = new GraphServiceClient(clientSecretCredential, scopes);
var requestBody = new SendMailPostRequestBody
                {
                    Message = new Message
                    {
                        Subject = "Reset Password",
                        Body = new ItemBody
                        {
                            ContentType = BodyType.Html,
                            Content = rendered
                        },
                        ToRecipients = new List<Recipient>
                        {
                            new Recipient { EmailAddress = new EmailAddress { Address = messageDto.Email } }
                        },
                        From = new Recipient { EmailAddress = new EmailAddress { Address = "noreply@myemailaddress" } }
                    }
                };
                await graphClient.Users["ObjectId"].SendMail.PostAsync(requestBody);

using Azure.Identity;
using Microsoft.Graph;
using Microsoft.Graph.Models;
var scopes = new[] { "https://graph.microsoft.com/.default" };
var clientId = "55bc1f7b-3bc1-439e-bddd-4xxxxxxxxxx";
var tenantId = "2773f7fd-d343-4afe-8230-exxxxxxxx";
var clientSecret = "xxxxxxxxxxxx";
var options = new ClientSecretCredentialOptions
{
    AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
};
var clientSecretCredential = new ClientSecretCredential(
    tenantId, clientId, clientSecret, options);
var graphClient = new GraphServiceClient(clientSecretCredential, scopes);
var requestBody = new Microsoft.Graph.Users.Item.SendMail.SendMailPostRequestBody
{
    Message = new Message
    {
        Subject = "Reset Password",
        Body = new ItemBody
        {
            ContentType = BodyType.Html,
            Content = "Please reset your password soon!",
        },
        ToRecipients = new List<Recipient>
        {
            new Recipient
            {
                EmailAddress = new EmailAddress
                {
                    Address = "sri@xxxxxxxxx.onmicrosoft.com",
                },
            },
        },
        From = new Recipient { EmailAddress = new EmailAddress { Address = "admin@xxxxxxxx.onmicrosoft.com" } }
    },
};
await graphClient.Users["7488bc42-6a7c-4ba2-a4c3-xxxxxxxx"].SendMail.PostAsync(requestBody);
Console.WriteLine("Mail sent successfully!");