Question

I can get both System.Net.Mail and System.Web.Mail to work with GMail, but I can’t get them both to work with smtp.att.yahoo.com.

I get the SMTP settings from my own Web.config keys. These settings work when I send using System.Web.Mail, but fail with System.Net.Mail.

    <add key='SmtpServer' value='smtp.att.yahoo.com'/>     <add key='SmtpServerAuthenticateUser' value='[e-mail]'/>     <add key='SmtpServerPort' value='465'/>     <add key='SmtpUseSSL' value='1'/>     <add key='SmtpServerAuthenticatePassword' value='MY PASSWORD'/> 

Here is the code that grabs my settings, and works with GMail, fails with att.yahoo:

        SmtpClient smtp;          if (!string.IsNullOrEmpty(Util.get_setting('SmtpServer', '')))         {            smtp = new SmtpClient(Util.get_setting('SmtpServer', ''));         }         else         {            smtp = new SmtpClient();         }           if (!string.IsNullOrEmpty(Util.get_setting('SmtpServerAuthenticatePassword', '')))            smtp.Credentials = new System.Net.NetworkCredential(                Util.get_setting('SmtpServerAuthenticateUser', ''),                 Util.get_setting('SmtpServerAuthenticatePassword', ''));          if (!string.IsNullOrEmpty(Util.get_setting('SmtpServerPort', '')))            smtp.Port = int.Parse(Util.get_setting('SmtpServerPort', ''));          if (Util.get_setting('SmtpUseSSL', '0') == '1')            smtp.EnableSsl = true;          smtp.Send(message); 

Is this my problem?

http://blogs.msdn.com/webdav_101/archive/2008/06/02/system-net-mail-with-ssl-to-authenticate-against-port-465.aspx

Answer 1

I’ve learned the answer. The answer is:

Because System.Net.Mail does not support ‘implicit’ SSL, only ‘explicit’ SSL.