通过.NET实现后台自动发送邮件功能的代码，可以将一些基础信息放到web.config文件中进行保存：
Web.config文件信息段：
<system.net>
<mailSettings>
<smtp deliveryMethod="Network" from="待发送邮箱地址">
<network host="待发送邮箱SMTP地址" userName="待发送邮箱地址" password="邮箱密码" defaultCredentials="true"/>
</smtp>
</mailSettings>
</system.net>
后台实现：
using System.Net.Mail;
using System.Configuration;
using System.Net.Configuration;
using System.Web.Configuration;
// addresses for send email.
string[] address = new string[] { "接收邮箱地址1", "接收邮箱地址2" };
// email body.
string emailBody = "Hello! Guys!";
// email subject.
string subject = "This is a test!";
// get the config info.
SmtpSection smtpSection = NetSectionGroup.GetSectionGroup(WebConfigurationManager.OpenWebConfiguration("~/web.config")).MailSettings.Smtp;
// save the mail object.
MailMessage mm = new MailMessage();
foreach (string item in address)
mm.To.Add(item);
mm.From = new MailAddress(smtpSection.From);
mm.BodyEncoding = System.Text.Encoding.UTF8;
mm.SubjectEncoding = System.Text.Encoding.UTF8;
mm.IsBodyHtml = true;
mm.Body = emailBody;
mm.Subject = subject;
// set and send email.
SmtpClient sc = new SmtpClient(smtpSection.Network.Host);
sc.DeliveryMethod = SmtpDeliveryMethod.Network;
sc.Credentials = new System.Net.NetworkCredential(smtpSection.Network.UserName, smtpSection.Network.Password);
sc.Send(mm);