smtpClient发信返回错误

[needsun]

我在.net 2008下用smtpClientfa类发送邮件，返回错误“发送邮件失败”，谁知道为什么，返回错误代码能否详细一下，而不是仅仅“发送邮件失败”，谢谢。
代码如下
try
{
System.Net.Mail.MailMessage myMail = new System.Net.Mail.MailMessage();
myMail = new System.Net.Mail.MailMessage(txtSEmail.Text.Trim(), txtCEmail.Text.Trim());
myMail.Subject = txtETitle.Text.Trim();
myMail.Body = txtEContent.Text.Trim();
System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(txtSService.Text.Trim(), Convert.ToInt32 (txtServicePort.Text.Trim()));
client.Credentials = new System.Net.NetworkCredential(txtUName.Text.Trim(), txtUPwd.Text.Trim());
client.Send(myMail);
MessageBox.Show("邮件发送成功！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
catch (System.Net.Mail.SmtpException ex)
{
MessageBox.Show(ex.Message, "发送邮件出错");
}

[liuhengwinner]

public struct MailItem
{
public string To;
public string From;
public string Subject;
public string body;
public string userName;
public string password;
public string smtpHost;
}

public class SendMail
{
public SendMail()
{
}
public void Send(MailItem aMailItem)
{
MailAddress from = new MailAddress(aMailItem.From);
MailAddress to = new MailAddress(aMailItem.To);
MailMessage message = new MailMessage(from, to);
message.Subject = aMailItem.Subject;
message.IsBodyHtml = true;
message.Body = aMailItem.body;
SmtpClient client = new SmtpClient(aMailItem.smtpHost);
//设置发送邮件身份验证方式
//注意如果发件人地址是[e-mail]，则用户名是abc而不是[e-mail]
client.Credentials = new NetworkCredential(aMailItem.userName, aMailItem.password);
client.Send(message);
}
}

[kainam]

高手快来啊 ， 我也正要的呢 ！

[ojekleen]

http://topic.csdn.net/u/20081019/22/6B52D26F-DA30-4756-8E4D-9283381CED94.html
http://topic.csdn.net/u/20081019/22/6B52D26F-DA30-4756-8E4D-9283381CED94.html

[needsun]

谢谢ojekleen ,但能否不用第三方gmail呢？

[needsun]

还有个幼稚的问题困扰我，如果我是机器A，通过邮件服务器C 发给机器B，为什么只要设置smtp,对机器c而言，不是还有接收处理吗？可否已经不归我管而归邮件服务器负责了呢？