1、在web.config中的<configuration>内加入如下配置信息（host—smtp服务地址；port—端口号；userName—用户名；password—密码。请自行修改）。
<system.net>
<mailSettings>
<smtp>
<network host="smtpserver" port="25" userName="uid" password="pwd" />
</smtp>
</mailSettings>
</system.net>
<mailSettings>
<smtp>
<network host="smtpserver" port="25" userName="uid" password="pwd" />
</smtp>
</mailSettings>
</system.net>
2、aspx页面HTML代码
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3、实例化一个MailMessage并设置其属性
MailMessage mm = new MailMessage(emailfrom.Text, emailto.Text);
mm.Subject = subject.Text;
mm.Body = body.Text;
// HTML格式
mm.IsBodyHtml = true;
// 添加附件
mm.Attachments.Add(new Attachment(attachment.PostedFile.InputStream, attachment.FileName));
/**//*其他如抄送、优先级之类的都可以在MailMessage类的属性中设置*/
4、实例化一个SmtpClient，调用其Send方法，参数为MailMessage对象
SmtpClient sc = new SmtpClient();
// 编程方式设置smtp（不用web.config）
// sc.Host = "";
// sc.Port = 25;
// sc.Credentials = new NetworkCredential("username", "password");
try
{
Response.Write(ex.ToString());
}
}
// 编程方式设置smtp（不用web.config）
// sc.Host = "";
// sc.Port = 25;
// sc.Credentials = new NetworkCredential("username", "password");
try
{
Response.Write(ex.ToString());
}
}