ASP.NET通过1and1 SMTP发送电子邮件

Question

I am having issues sending an email through 1and1 smtp

Here is my code that i use in my asp.net mvc application: (When I used this code with gmail it works fine, but now I have to use 1and1 and it won't work :(

public void Send(Inquiry inquiry)
    {
        SmtpClient smtpClient = new SmtpClient ("Smtp.1and1.com", 587);
        smtpClient.UseDefaultCredentials = false;
        smtpClient.Credentials = new System.Net.NetworkCredential("mail@mywebsite.com", "mypassword");

        smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
        smtpClient.EnableSsl = true;
        MailMessage mail = new MailMessage();


        mail.From = new MailAddress("sales@mywebsite.com", "myname");
        mail.To.Add(new MailAddress("sales@mywebsite.com"));
        mail.Subject = $"New inquiry from {inquiry.Name}";
        mail.Body = $"{inquiry.Message}\r " +
            $"Recieved: {inquiry.Date}";
        mail.ReplyToList.Add(new MailAddress(inquiry.Email));


        smtpClient.Send(mail);
    }

The error that I get is:

SmtpException: Error in processing. The server response was: Requested action aborted: local error in processing

System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, string response)

Answer 1

This is my changes and now it works!

Mail.from and mail.to were different addresses from the email used to login...

Here us the fixed code:

 public void Send(Inquiry inquiry)
    {
        SmtpClient smtpClient = new SmtpClient ("smtp.1and1.com",587);
        smtpClient.UseDefaultCredentials = false;
        smtpClient.Credentials = new System.Net.NetworkCredential("mail@mywebsite.com", "mypassword");

        smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
        smtpClient.EnableSsl = true;
        MailMessage mail = new MailMessage();

        //Setting From , To and CC
        mail.From = new MailAddress("mail@mywebsite.com", "myname");
        mail.To.Add(new MailAddress("mail@mywebsite.com"));
        mail.Subject = $"New inquiry from {inquiry.Name}";
        mail.Body = $"From: {inquiry.Name}\n" +
            $"Phone number: {inquiry.PhoneNumber} \n" +
            $"Message: {inquiry.Message}\n \n" +

            $"Recieved: {inquiry.Date}";
       mail.ReplyToList.Add(new MailAddress(inquiry.Email));


        smtpClient.Send(mail);
    }

Answer 2

From 1and1 error page

451 Requested action aborted: local error in processing:

The email could not be delivered successfully because the service was temporarily unavailable. Please try again later.

Please note : For emails to be delivered successfully, it is important, among other things, that the resolution of the DNS query is always answered quickly by the responsible DNS service. If problems persist, you should therefore inform the administrator of the sender domain so that he can ensure a fast name resolution.