asp.net发送邮件失败，求解

代码如下：
public Email()
{
//
//TODO: 在此处添加构造函数逻辑
//

From = "XXXXX@126.com";
Password = "123456";
Title = "标题";
SmtpStr = "smtp.126.com";
Port = 25;
}

private string From; //邮件帐号
private string Password; //邮件密码
private string Title; //发送标题
private string SmtpStr;
private int Port;

public string To; //接收者邮箱
public string Body; //发送邮件内容

public void EmailSend()
{
SmtpClient smtp = new SmtpClient();
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.EnableSsl = false;
smtp.Host = SmtpStr;
smtp.Port = Port;
smtp.UseDefaultCredentials = true;
smtp.Credentials = new NetworkCredential(From, Password);
MailMessage mm = new MailMessage();
mm.Priority = MailPriority.High;

mm.From = new MailAddress(From, Title, Encoding.GetEncoding(936));

foreach (string item in To.Split(','))
{
mm.CC.Add(new MailAddress(item, From, Encoding.GetEncoding(936)));
}
mm.Subject = Title;//"邮件标题";
mm.SubjectEncoding = Encoding.GetEncoding(936);
//936是简体中文的pagecode，如果是英文标题，这句可以忽略不用
mm.IsBodyHtml = true;
mm.BodyEncoding = Encoding.GetEncoding(936);
mm.Body = Body;
smtp.Send(mm);

}



获取的异常信息是：

用户代码未处理 System.Net.Mail.SmtpException
Message="发送邮件失败。"
Source="System"
StackTrace:
在 System.Net.Mail.SmtpClient.Send(MailMessage message)
在 Tec.Com.Email.EmailSend() 位置 D:\WorkSpaces\考勤系统\Attendance\Tec.Com\Email.cs:行号 116
在 Tec.BLL.Email.sendEmail(Int32 type, UserInfo user) 位置 D:\WorkSpaces\考勤系统\Attendance\Tec.BLL\Email.cs:行号 48
在 fillForm_addleaveForm.ButtonSubmit_Click(Object sender, EventArgs e) 位置 d:\WorkSpaces\考勤系统\Attendance\WebSite\fillForm\addLeaveForm.aspx.cs:行号 332
在 System.Web.UI.WebControls.Button.OnClick(EventArgs e)
在 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
在 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
在 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
在 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
在 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
InnerException: System.FormatException
Message="在头值中找到无效的字符。"
Source="System"
StackTrace:
在 System.Net.Mime.HeaderCollection.Set(String name, String value)
在 System.Net.Mail.Message.PrepareHeaders(Boolean sendEnvelope)
在 System.Net.Mail.Message.Send(BaseWriter writer, Boolean sendEnvelope)
在 System.Net.Mail.SmtpClient.Send(MailMessage message)
InnerException:

[code=csharp]

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