string file = @"c:\ok.xls";
string to = "***@sina.com";
string from = "***@163.com";
string subject = "dfsdfsafdsfasfds.";
string body = @"Using this new feature, you can send an e-mail message from an application very easily.";
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(from, to, subject, body);
message.From = new MailAddress("***@163.com", "逄瑞锋");
Attachment data = new Attachment(file, MediaTypeNames.Application.Octet);
// Add the file attachment to this e-mail message.
message.Attachments.Add(data);
SmtpClient client = new SmtpClient("smtp.163.com", 25);
// Credentials are necessary if the server requires the client
// to authenticate before it will send e-mail on the client's behalf.
client.Credentials = new NetworkCredential("username", "password");
client.Send(message);
data.Dispose();