Sending mails doesn't work. I'm not sure if it's something with client settings or mail server...

When using Gmail SMTP server I got "Connection closed" exception, when changing port to 587 I get "Authentication required" message. What's more interesting when changing SMTP server to something different (smtp.poczta.onet.pl) I get "Time out" exception after ~100s

Here's the code:

protected void SendMessage(object sender, EventArgs e)
{
        // receiver address
        string to = "******@student.uj.edu.pl";

        // mail (sender) address
        string from = "******@gmail.com";

        // SMTP server address
        string server = "smtp.gmail.com";

        // mail password
        string password = "************";

        MailMessage message = new MailMessage(from, to);

        // message title
        message.Subject = TextBox1.Text;

        // message body
        message.Body = TextBox3.Text   " otrzymane "   DateTime.Now.ToString()    " od: "   TextBox2.Text;

        SmtpClient client = new SmtpClient(server, 587);
        client.Credentials = new System.Net.NetworkCredential(from, password);
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        client.UseDefaultCredentials = false;
        client.EnableSsl = true;

        try
        {
            client.Send(message);

            // ui confirmation
            TextBox3.Text = "Wysłano wiadmość!";

            // disable button
            Button1.Enabled = false;
        }
        catch (Exception ex)
        {
            // error message
            TextBox3.Text = "Problem z wysłaniem wiadomości ("   ex.ToString()   ")";
        }
 }

I've just read that google don't support some less secure apps (3rd party apps to sign in to Google Account using username and password only) since 30/05/22. Unfortunately can't change it because I have two-stage verification account. Might it be connected? Or is it something with my code?

CodePudding user response：

Gmail doesn't allow, or want you to do that with passwords anymore. They ask you to create a credentials files and then use a token.json to send email.

Using their API from Google.Apis.Gmail.v1 - from Nuget. Here is a method I made and test that is working with gmail.

void Main()
{
    UserCredential credential;

    using (var stream =
        new FileStream(@"C:\credentials.json", FileMode.Open, FileAccess.Read))
    {
        // The file token.json stores the user's access and refresh tokens, and is created
        // automatically when the authorization flow completes for the first time.
        string credPath = "token.json";
        credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
            GoogleClientSecrets.Load(stream).Secrets,
            Scopes,
            "user",
            CancellationToken.None,
            new FileDataStore(credPath, true)).Result;
        Console.WriteLine("Credential file saved to: "   credPath);
    }

    // Create Gmail API service.
    var service = new GmailService(new BaseClientService.Initializer()
    {
        HttpClientInitializer = credential,
        ApplicationName = ApplicationName,
    });

    // Define parameters of request.
    UsersResource.LabelsResource.ListRequest request = service.Users.Labels.List("me");

    // List labels.
    IList<Label> labels = request.Execute().Labels;
    Console.WriteLine("Labels:");
    if (labels != null && labels.Count > 0)
    {
        foreach (var labelItem in labels)
        {
            Console.WriteLine("{0}", labelItem.Name);
        }
    }
    else
    {
        Console.WriteLine("No labels found.");
    }
    //Console.Read();
    var msg = new Google.Apis.Gmail.v1.Data.Message();
    MimeMessage message = new MimeMessage();
    
    message.To.Add(new MailboxAddress("", "toemail.com"));
    message.From.Add(new MailboxAddress("Some Name", "[email protected]"));
    message.Subject = "Test email with Mime Message";
    message.Body = new TextPart("html") {Text = "<h1>This</h1> is a body..."};
    
    var ms = new MemoryStream();
    message.WriteTo(ms);
    ms.Position = 0;
    StreamReader sr = new StreamReader(ms);
    string rawString = sr.ReadToEnd();

    byte[] raw = System.Text.Encoding.UTF8.GetBytes(rawString);
    msg.Raw = System.Convert.ToBase64String(raw);
    
    var res = service.Users.Messages.Send(msg, "me").Execute();
    
    res.Dump();


}
static string[] Scopes = { GmailService.Scope.GmailSend, GmailService.Scope.GmailLabels, GmailService.Scope.GmailCompose, GmailService.Scope.MailGoogleCom};
static string ApplicationName = "Gmail API Send Email";

CodePudding user response：

Enable 2FA on your email and generate a password for your application using the link. As far as I know, login and password authorization using unauthorized developer programs is no longer supported by Google.

CodePudding user response：

Can you ping the smpt server from your machine or the machine you deploy the code from? THis could be a DNS issue.