Question

I am using this code for sending email in asp.net:

Using System.Net.Mail

public string SendEmail()
{
    SmtpClient obj = new SmtpClient();
    MailMessage Mailmsg = new MailMessage();
    Mailmsg.To.Clear();

    Recievers = new MailAddressCollection();
    Recievers.Add(txtToAddress.Text);
    SenderName = "Info";
    SenderEmail = txtFromAddress.Text;
    Subject = "subj";
    Body = "body";
    UseBcc = false;

    if (UseBcc)
    {
        foreach (MailAddress RecieverItem in Recievers)
        {
            Mailmsg.Bcc.Add(RecieverItem);
        }
    }
    else
    {
        foreach (MailAddress RecieverItem in Recievers)
        {
            Mailmsg.To.Add(RecieverItem);
        }
    }

    Mailmsg.From = new MailAddress(SenderEmail, SenderName, System.Text.Encoding.UTF8);
    Mailmsg.Subject = Subject;
    Mailmsg.SubjectEncoding = Encoding.UTF8;
    Mailmsg.BodyEncoding = System.Text.Encoding.UTF8;
    Mailmsg.IsBodyHtml = false;

    obj.Host = mail.domain.com;

    System.Net.NetworkCredential BasicAuthenticationInfo = new System.Net.NetworkCredential("[e-mail]", "password");

    obj.UseDefaultCredentials = false;
    obj.Credentials = BasicAuthenticationInfo;

    Mailmsg.Body = Body;
    Mailmsg.IsBodyHtml = true;
    try
    {
        obj.Send(Mailmsg);
        return "sent";
    }
    catch (Exception ex)
    {
        return ex.ToString();
    }
}

It correctly sends emails to recievers which are defined in my domain (like [e-mail]), but I cannot send email to other mail servers (like [e-mail]).

What is wrong in my code?

(May it relate to SmtpClient properties? I have set smtpclient.host to mail.mydomain.com
and use username and password of one of my mail accounts which are defined in my domain)

Thanks

Answer 1

It must be something related to your exchange server. there are transport rules in exchange which define how you can communicate with the outside world.

http://www.msexchange.org/articles_tutorials/exchange-server-2007/management-administration/restricting-users-send-receive-external-messages-exchange-server-2007.html

you must be getting some exception while sending email to outside network

System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: 5.1.1 User unknown
   at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException& exception)

If this is error you are getting this mean your exchange is not supported to send email directly to outside network. as I am no MS exchange expert but i have been using a exchange server configured in my network that can’t send email to outside network but we enable email forwarding to contacts.

May be this can help you. http://www.petri.co.il/configuring-exchange-2007-send-connectors.htm

also i would suggest you share this problem on https://serverfault.com/