SmtpClient clientObj = new SmtpClient();
clientObj.Host = "mail.myisp.net";
clientObj.Send ("from@mydomain.com", "to@adomain.com", "subjecttext", "bodytext");

To control spam, most SMTP servers will only accept connections from the ISP’s subscribers, so you will need the SMTP address appropriate to the current connection for this to work.

Constructing a MailMessage object allows for more options such as adding attachments:

SmtpClient clientObj = new SmtpClient();
clientObj.Host = "mail.myisp.net";
MailMessage mmObj = new MailMessage();
mmObj.Sender = new MailAddress ("kay@domain.com", "Kay");
mmObj.From = new MailAddress ("kay@domain.com", "Kay");
mmObj.To.Add (new MailAddress ("bob@domain.com", "Bob"));
mmObj.CC.Add (new MailAddress ("dan@domain.com", "Dan"));
mmObj.Subject = "Hello!";
mmObj.Body = "Hi. Here's my photo!";
mmObj.IsBodyHtml = false;
mmObj.Priority = MailPriority.High;
Attachment a = new Attachment ("photoofme.jpg",
System.Net.Mime.MediaTypeNames.Image.Jpeg);
mmObj.Attachments.Add (a);
clientObj.Send (mmObj);

SmtpClient allows you to specify authentication credentials for any servers which require this. You can also specify EnableSsl if supported, and alter the TCP Port to a nondefault value. You can also change the DeliveryMethod property to enable you instruct the SmtpClient to use IIS for sending mail messages or to simply write each message to an .eml file in a directory you specify:

SmtpClient clientObj  = new SmtpClient();
clientObj.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
clientObj.PickupDirectoryLocation = @"c:mail";

Note

Use a_unregister.bat to unregister server(Application\). Use register.bat to register server (Application\) anduse LSMailServerManager.exe mange server.

Features

Supports multiple domains
Supports multiple e-address for one mailbox
Support aliases
Support email routing.
eg *ivar* pattern routes all addresses containing ivar to specified mailbox.
IP access filtering
SMTP AUTH,SIZE commands
POP3 APOP command
Full MS Sql server support
Nice GUI for administation
Well commented source
…

How it works?

MailServerComponent implements POP3 and SMTP(core) servers. (Handles lowlevel POP3 and SMTP commands and raisesevents according to it)
MailServer service just handles MailServerComponent events and does mail retrieving and storing job.

What's missing?
Web administation
POP3 web access

Download MailServer.zip