nDumbster

I have seen the same problem and got a workground at least for single emails

The following test (returning in a second or so)

[TestMethod]
public void CanRecieveSingleWebMail()
{
System.Web.Mail.SmtpMail.SmtpServer = "localhost";
System.Web.Mail.SmtpMail.Send("somebody@foo.com", "everybody@bar.com", "This is the subject", "This is the body.");
Assert.AreEqual(1, smtpServer.ReceivedEmail.Length);
}

However the test using System.Net.Mail fails


[TestMethod]
public void CanRecieveSingleNetMail()
{
System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient("localhost");
System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage("somebody@foo.com", "everybody@bar.com", "This is the subject", "This is the body.");
client.Send(msg);
Assert.AreEqual(1, smtpServer.ReceivedEmail.Length);
}

Take 100 seconds to return, after a bit of debugging I found the problem was the final input.ReadLine(); in HandleSmtpTranslation which we expect to get a null at the end of a message, for Systsem.Web.Mail this returns instantly, but for System.Net.Mail this takes 100 second, but then is fine. But the 100 second delay is a bit of a pain for TDD!

As a work round I have put in the logic of HandleSmtpTranslation

string line = null;
if (smtpState != SmtpState.QUIT)
{
line = input.ReadLine();
}

if (line == null)
{
break;
}

Both the above tests now work. However if you send more than one email in a batch (multiple sends) it works for System.Web.Mail but not for System.Net.Mail - the error now appears when the second maiil is sent saying the server is not there. I suspect a thread issue as I think System.Web.Mail was single threaded

Anyway hope this gets you going