Use SSL with SMTP

Mail.dll SMTP client supports Secure Socket Layer (SSL) and Transport Layer Security (TLS) protocols to authenticate the server and secure client-server communication.

There are two modes in which Mail.dll can work:

• Implicit - where Mail.dll SMTP client immediately connects using secure channel,
• Explicit - where Mail.dll SMTP client connects on unsecured channel first and then secures the communication by issuing STARTTLS command.

In both cases, by default, either Secure Sockets Layer (SSL) 3.0 or Transport Layer Security (TLS) 1.0 are acceptable for secure communication. You can change the defaults by using Smtp.SSLConfiguration property.

Smtp client may decide to secure the channel, if SMTP server explicitly forbids logging-in on unsecured channel and you are using UseBestLogin method.

Implicit mode:

// C# version

using Limilabs.Mail;
using Limilabs.Client.POP3;

class Program
{
    static void Main(string[] args)
    {
        using (Smtp smtp = new Smtp())
        {
            smtp.ConnectSSL("server.example.com");

            smtp.Login("user", "password");

            MailBuilder builder = new MailBuilder();
            builder.Text = "text";
            builder.From.Add(new MailBox("from@example.com"));
            builder.To.Add(new MailBox("to@example.com"));

            IMail email = builder.Create();

            smtp.SendMessage(email);

            smtp.Close();
        }
    }
};

' VB.NET version

Imports Limilabs.Mail
Imports Limilabs.Client.SMTP

Public Module Module1
    Public Sub Main(ByVal args As String())

        Using smtp As New Smtp()

            smtp.ConnectSSL("server.example.com")

            smtp.Login("user", "password")

            Dim builder As New MailBuilder()
            builder.Text = "text"
            builder.From.Add(New MailBox("from@example.com"))
            builder.[To].Add(New MailBox("to@example.com"))

            Dim email As IMail = builder.Create()

            smtp.SendMessage(email)

            smtp.Close()
        End Using

    End Sub
End Module

Explicit mode:

// C# version

using Limilabs.Mail;
using Limilabs.Mail.Headers;
using Limilabs.Client.SMTP;

class Program
{
    static void Main(string[] args)
    {
        using (Smtp smtp = new Smtp())
        {
            smtp.Connect("server.example.com");

            smtp.StartTLS();

            smtp.Login("user", "password");

            MailBuilder builder = new MailBuilder();
            builder.Text = "text";
            builder.From.Add(new MailBox("from@example.com"));
            builder.To.Add(new MailBox("to@example.com"));

            IMail email = builder.Create();

            smtp.SendMessage(email);

            smtp.Close();
        }
    }
};

' VB.NET version

Imports Limilabs.Mail
Imports Limilabs.Mail.Headers
Imports Limilabs.Client.SMTP

Public Module Module1
    Public Sub Main(ByVal args As String())

        Using smtp As New Smtp()
            smtp.Connect("server.example.com")

            smtp.StartTLS()

            smtp.Login("user", "password")

            Dim builder As New MailBuilder()
            builder.Text = "text"
            builder.From.Add(New MailBox("from@example.com"))
            builder.[To].Add(New MailBox("to@example.com"))

            Dim email As IMail = builder.Create()

            smtp.SendMessage(email)

            smtp.Close()
        End Using

    End Sub
End Module

If you are using self-signed certificates you may encounter this error: The remote certificate is invalid according to the validation procedure.

Tags: C#, Mail.dll, SMTP, SSL, VB.NET

This entry was posted on Monday, October 25th, 2010 at 15:50 and is filed under Component. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.