SmtpClient "Request failed; Mailbox unavailable"

Question

Im trying to send and Email with SmtpClient at the yahoo smtp server

"smtp.mail.yahoo.com", 587

The first time trying, I got an email telling me to change my account settings to allow smtp requests to work, but after doing that, the mailbox is unavailable.

SendMail method:

public void SendMail(string name, string from, string to, string subject, string content)
    {
        try
        {
            using (var mail = new MailMessage())
            {
                const string email = @"mail@yahoo.com";
                const string pw = "***";

                var login = new NetworkCredential(email, pw);

                mail.From = new MailAddress(from);
                mail.To.Add(new MailAddress(to));
                mail.Subject = subject;
                mail.Body = content;
                mail.IsBodyHtml = true;

                try
                {
                    using (var client = new SmtpClient("smtp.mail.yahoo.com", 587))
                    {
                        client.EnableSsl = true;
                        client.DeliveryMethod = SmtpDeliveryMethod.Network;
                        client.UseDefaultCredentials = false;
                        client.Credentials = login;
                        client.Send(mail);
                    }
                }
                finally
                {
                    mail.Dispose();
                }
            }
        }
        catch(Exception ex)
        {

        }
    }

Action:

[HttpPost]
    public ActionResult ContactSend(Mail mail)
    {
        if(ModelState.IsValid)
        {
            var toAdress = @"tomail@yahoo.de";
            var fromAdress = mail.Email;
            var subject = mail.Betreff;
            var name = mail.Name;
            var content = new StringBuilder();
            content.Append("Name: " + name + "\n");
            content.Append("Email: " + fromAdress + "\n\n");
            content.Append(mail.Content);

            SendMail(name, fromAdress, toAdress, subject, content.ToString());

        }

        return RedirectToAction("Kontakt", "Home");
    }

Checked all the login information and since i got an email from yahoo the first time i tried it they seem to work.

Exception:

• Response {System.Web.HttpResponseWrapper} System.Web.HttpResponseBase {System.Web.HttpResponseWrapper}
• ex {"Postfach nicht verfügbar. Die Serverantwort war: Request failed; Mailbox unavailable"} System.Exception {System.Net.Mail.SmtpException}
• Data {System.Collections.ListDictionaryInternal} System.Collections.IDictionary {System.Collections.ListDictionaryInternal} HResult -2146233088 int HelpLink null string
• InnerException null System.Exception Message "Postfach nicht verfügbar. Die Serverantwort war: Request failed; Mailbox unavailable" string Source "System" string StackTrace " bei System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)\r\n bei System.Net.Mail.MailCommand.Send(SmtpConnection conn, Byte[] command, MailAddress from, Boolean allowUnicode)\r\n bei System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)\r\n bei System.Net.Mail.SmtpClient.Send(MailMessage message)\r\n bei Makler.Controllers.HomeController.SendMail(String name, String from, String to, String subject, String content) in C:\Users\Joshua\source\repos\Makler\Makler\Controllers\HomeController.cs:Zeile 90." string StatusCode MailboxUnavailable System.Net.Mail.SmtpStatusCode
• TargetSite {Void CheckResponse(System.Net.Mail.SmtpStatusCode, System.String)} System.Reflection.MethodBase {System.Reflection.RuntimeMethodInfo}
• Static members
• Non-Public members
• this {Makler.Controllers.HomeController} Makler.Controllers.HomeController

Answer 1

"Mailbox Unavailable" is a message from Yahoo's mail server, but means very little except that they didn't want to talk to you.

The "To:" address might be out of space or spelled wrong, or they might not like your IP address or any of a hundred other things.

You can google for yahoo postmaster help and see if they have any suggestions.

You have successfully connected but they refused to accept your mail. You would need actual information to know why.