Create and send an email programmatically with the new Outlook

FrancoisBard 

There is limited VSTO support for Outlook, please refer on C#:

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using Newtonsoft.Json.Linq;

class Program
{
private static async Task Main(string[] args)
{
var accessToken = "YOUR_ACCESS_TOKEN"; // Obtain this from the OAuth2 flow
var graphClient = new HttpClient();
graphClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

var email = new JObject
{
["message"] = new JObject
{
["subject"] = "Test Email with Attachment",
["body"] = new JObject
{
["contentType"] = "Text",
["content"] = "This is a test email with an attachment."
},
["toRecipients"] = new JArray
{
new JObject
{
["emailAddress"] = new JObject
{
["address"] = "email address removed for privacy reasons"
}
}
},
["attachments"] = new JArray
{
new JObject
{
["@odata.type"] = "#microsoft.graph.fileAttachment",
["name"] = "test.txt",
["contentBytes"] = Convert.ToBase64String(System.IO.File.ReadAllBytes("path/to/your/file.txt"))
}
}
},
["saveToSentItems"] = "true"
};

var response = await graphClient.PostAsync("https://graph.microsoft.com/v1.0/me/sendMail", new StringContent(email.ToString(), System.Text.Encoding.UTF8, "application/json"));
if (response.IsSuccessStatusCode)
{
Console.WriteLine("Email sent successfully.");
}
else
{
Console.WriteLine($"Error sending email: {response.ReasonPhrase}");
}
}
}