How can I send emails through SSL SMTP with the .NET Framework ?

Question

Is there a way with the .NET Framework to send emails through an SSL SMTP server on port 465?

The usual way:

System.Net.Mail.SmtpClient _SmtpServer = new System.Net.Mail.SmtpClient("tempurl.org");
_SmtpServer.Port = 465;
_SmtpServer.EnableSsl = true;
_SmtpServer.Credentials = new System.Net.NetworkCredential("username", "password");
_SmtpServer.Timeout = 5000;
_SmtpServer.UseDefaultCredentials = false;

MailMessage mail = new MailMessage();
mail.From = new MailAddress(from);
mail.To.Add(to);
mail.CC.Add(cc);
mail.Subject = subject;
mail.Body = content;
mail.IsBodyHtml = useHtml;
_SmtpServer.Send(mail);

times out:

System.Net Verbose: 0 : [1024] SmtpClient::.ctor(host=ssl0.ovh.net, port=465)
System.Net Information: 0 : [1024] Associating SmtpClient#64923656 with SmtpTransport#44624228
System.Net Verbose: 0 : [1024] Exiting SmtpClient::.ctor()  -> SmtpClient#64923656
System.Net Information: 0 : [1024] Associating MailMessage#17654054 with Message#52727599
System.Net Verbose: 0 : [1024] SmtpClient#64923656::Send(MailMessage#17654054)
System.Net Information: 0 : [1024] SmtpClient#64923656::Send(DeliveryMethod=Network)
System.Net Information: 0 : [1024] Associating SmtpClient#64923656 with MailMessage#17654054
System.Net Information: 0 : [1024] Associating SmtpTransport#44624228 with SmtpConnection#14347911
System.Net Information: 0 : [1024] Associating SmtpConnection#14347911 with ServicePoint#51393439
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Socket(InterNetwork#2)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Socket() 
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Socket(InterNetworkV6#23)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#23264094::Socket() 
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Connect(20:465#337754884)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Connect() 
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Close()
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Dispose()
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#23264094::Close() 
System.Net Information: 0 : [1024] Associating SmtpConnection#14347911 with SmtpPooledStream#14303791
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Receive()
System.Net.Sockets Verbose: 0 : [2404] Socket#26756241::Dispose()
System.Net.Sockets Error: 0 : [1024] Exception in the Socket#26756241::Receive - A blocking operation was interrupted by a call to WSACancelBlockingCall
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Receive()   -> 0#0
System.Net Error: 0 : [1024] Exception in the SmtpClient#64923656::Send - Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall.
System.Net Error: 0 : [1024]    at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.DelegatedStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.Net.BufferedReadStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)
   at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)
   at System.Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)
   at System.Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)
   at System.Net.Mail.SmtpClient.GetConnection()
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
System.Net Verbose: 0 : [1024] Exiting SmtpClient#64923656::Send() 
System.Net Information: 0 : [1024] Associating MailMessage#49584532 with Message#19699911

I googled around and found that System.Net.Mail supports connections on port 587 (default port for Explicit SSL that starts unencrypted then issues a STARTDLS then switches to an Encrypted connection: RFC 2228), but doesn't support Implicit SSL (entire connection is wrapped in an SSL layer)...

Answer 1

It works with System.Web.Mail (which is marked as obsolete):

private const string SMTP_SERVER     = "http://schemas.microsoft.com/cdo/configuration/smtpserver";
private const string SMTP_SERVER_PORT   = "http://schemas.microsoft.com/cdo/configuration/smtpserverport";
private const string SEND_USING   = "http://schemas.microsoft.com/cdo/configuration/sendusing";
private const string SMTP_USE_SSL    = "http://schemas.microsoft.com/cdo/configuration/smtpusessl";
private const string SMTP_AUTHENTICATE  = "http://schemas.microsoft.com/cdo/configuration/smtpauthenticate";
private const string SEND_USERNAME   = "http://schemas.microsoft.com/cdo/configuration/sendusername";
private const string SEND_PASSWORD   = "http://schemas.microsoft.com/cdo/configuration/sendpassword";

System.Web.Mail.MailMessage mail = new System.Web.Mail.MailMessage();

mail.Fields[SMTP_SERVER] = "tempurl.org";
mail.Fields[SMTP_SERVER_PORT] = 465;
mail.Fields[SEND_USING] = 2;
mail.Fields[SMTP_USE_SSL] = true;
mail.Fields[SMTP_AUTHENTICATE] = 1;
mail.Fields[SEND_USERNAME] = "username";
mail.Fields[SEND_PASSWORD] = "password";

System.Web.Mail.SmtpMail.Send(mail);

What is your point of view regarding obsolete namespace usage?

Answer 2

Here is an example of how to send email through GMail which also uses SSL/465. Minor tweaking of the code below should work!

using System.Web.Mail;
using System;
public class MailSender
{
    public static bool SendEmail(
        string pGmailEmail, 
        string pGmailPassword, 
        string pTo, 
        string pSubject,
        string pBody, 
        System.Web.Mail.MailFormat pFormat,
        string pAttachmentPath)
    {
    try
    {
        System.Web.Mail.MailMessage myMail = new System.Web.Mail.MailMessage();
        myMail.Fields.Add
            ("http://schemas.microsoft.com/cdo/configuration/smtpserver",
                          "smtp.gmail.com");
        myMail.Fields.Add
            ("http://schemas.microsoft.com/cdo/configuration/smtpserverport",
                          "465");
        myMail.Fields.Add
            ("http://schemas.microsoft.com/cdo/configuration/sendusing",
                          "2");
        //sendusing: cdoSendUsingPort, value 2, for sending the message using 
        //the network.

        //smtpauthenticate: Specifies the mechanism used when authenticating 
        //to an SMTP 
        //service over the network. Possible values are:
        //- cdoAnonymous, value 0. Do not authenticate.
        //- cdoBasic, value 1. Use basic clear-text authentication. 
        //When using this option you have to provide the user name and password 
        //through the sendusername and sendpassword fields.
        //- cdoNTLM, value 2. The current process security context is used to 
        // authenticate with the service.
        myMail.Fields.Add
        ("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate","1");
        //Use 0 for anonymous
        myMail.Fields.Add
        ("http://schemas.microsoft.com/cdo/configuration/sendusername",
            pGmailEmail);
        myMail.Fields.Add
        ("http://schemas.microsoft.com/cdo/configuration/sendpassword",
             pGmailPassword);
        myMail.Fields.Add
        ("http://schemas.microsoft.com/cdo/configuration/smtpusessl",
             "true");
        myMail.From = pGmailEmail;
        myMail.To = pTo;
        myMail.Subject = pSubject;
        myMail.BodyFormat = pFormat;
        myMail.Body = pBody;
        if (pAttachmentPath.Trim() != "")
        {
            MailAttachment MyAttachment = 
                    new MailAttachment(pAttachmentPath);
            myMail.Attachments.Add(MyAttachment);
            myMail.Priority = System.Web.Mail.MailPriority.High;
        }

        System.Web.Mail.SmtpMail.SmtpServer = "smtp.gmail.com:465";
        System.Web.Mail.SmtpMail.Send(myMail);
        return true;
    }
    catch (Exception ex)
    {
        throw;
    }
}
}

Answer 3

If it's Implicit SSL, it looks like it can't be done with System.Net.Mail and isn't supported as of yet.

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

To check if it's Implicit SSL try this.

Answer 4

What a solution man! I LOVE obsolete namespace when it saves my ass! Three hours in debugging before finding out this post ...

Thank you so much!

Answer 5

You can also connect via port 465, but due to some limitations of the System.Net.Mail namespace you may have to alter your code. This is because the namespace does not offer the ability to make implicit SSL connections. This is discussed at http://blogs.msdn.com/b/webdav_101/archive/2008/06/02/system-net-mail-with-ssl-to-authenticate-against-port-465.aspx.

It is possible to make implicit connections without having to use the now obsolete System.Web.Mail namespace, but you have to access the Microsoft CDO (Collaborative Data Object). I have supplied an example of how to use the CDO in another discussion (GMail SMTP via C# .Net errors on all ports).

Hope this helps!

Answer 6

How can I use this code to authenticate with MD5 Challenge/Response????? Please help