SimpleSmtpServer server;
        public BatchEmailTest()
        {
            server = null;
            server = SimpleSmtpServer.Start();
        }

        [Test]
        public void TestBatchEmail()
        {
            ISiteUserService iSiteUser = ServiceFactory.GetInstance().GetService(typeof(ISiteUserService)) as ISiteUserService;
            Hashtable hs = new Hashtable();
            IList mailList = iSiteUser.GetBatchEmailList(hs);
            SmtpMail.SmtpServer = "localhost";

            for (int i = 0; i < mailList.Count; i++)
            {
                //send mail
                MailMessage message = new MailMessage();
                message.Subject = "Subject";
                message.Body = "Send Body..";
                message.From = "test@cwave.com";
                message.To = mailList[i].ToString();
                SmtpMail.Send(message);
            }

            Assert.AreEqual(mailList.Count, server.ReceivedEmailCount);
            for (int j = 0; j < server.ReceivedEmailCount; j++)
            {
                SmtpMessage email = server.ReceivedEmail[j];
                Assert.AreEqual("<test@cwave.com>", email.Headers["From"]);
                Assert.AreEqual("<" + mailList[j].ToString() + ">", email.Headers["To"]);
                Assert.AreEqual("Subject", email.Headers["Subject"]);
                Assert.AreEqual("Send Body..", email.Body);
            }

  
        }
        [TestFixtureTearDown]
        public void TearDown()
        {
            if (server != null)
                server.Stop();
        }

    }

希望对你有用!