C#發(fā)送郵件的功能在網(wǎng)上找了很多也有利用socket的 ，試了一下不行的原因是smtp服務(wù)器的問題。在這里我用了mailmessage和搜狐的stmp.sohu.com。源碼如下：

    protected void Button1_Click(object sender, EventArgs e)
    {

        string from = ******@sohu.com;
        string fromer = "發(fā)件人";
        string to = "*****@126.com";
        string toer = "收件人";
        string Subject = "郵件標(biāo)題";
        string file="附件地址";
        string Body ="發(fā)送內(nèi)容";
        string SMTPHost = "smtp.sohu.com";
        string SMTPuser = "******@sohu.com";
        string SMTPpass = "*******";
        sendmail(from, fromer, to, toer, Subject, Body,file,SMTPHost, SMTPuser, SMTPpass);
    }

    /// <summary>
    /// C#發(fā)送郵件函數(shù)
    /// </summary>
    /// <param name="from">發(fā)送者郵箱</param>
    /// <param name="fromer">發(fā)送人</param>
    /// <param name="to">接受者郵箱</param>
    /// <param name="toer">收件人</param>
    /// <param name="Subject">主題</param>
    /// <param name="Body">內(nèi)容</param>
    /// <param name="file">附件</param>
    /// <param name="SMTPHost">smtp服務(wù)器</param>
    /// <param name="SMTPuser">郵箱</param>
    /// <param name="SMTPpass">密碼</param>

    /// <returns></returns>
    public bool sendmail(string sfrom, string sfromer, string sto, string stoer, string sSubject, string sBody, string sfile, string sSMTPHost, string sSMTPuser, string sSMTPpass)
    {
        ////設(shè)置from和to地址
        MailAddress from = new MailAddress(sfrom, sfromer);
        MailAddress to = new MailAddress(sto, stoer);

        ////創(chuàng)建一個(gè)MailMessage對象
        MailMessage oMail = new MailMessage(from, to);

        //// 添加附件
        if (sfile != "")
        {
            oMail.Attachments.Add(new Attachment(sfile));
        }

        ////郵件標(biāo)題
        oMail.Subject = sSubject;

        ////郵件內(nèi)容
        oMail.Body = sBody;

        ////郵件格式
        oMail.IsBodyHtml = false;

        ////郵件采用的編碼
        oMail.BodyEncoding = System.Text.Encoding.GetEncoding("GB2312");

        ////設(shè)置郵件的優(yōu)先級為高
        oMail.Priority = MailPriority.High;

        ////發(fā)送郵件
        SmtpClient client = new SmtpClient();
        ////client.UseDefaultCredentials = false;
        client.Host = sSMTPHost;
        client.Credentials = new NetworkCredential(sSMTPuser, sSMTPpass);
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        try
        {
            client.Send(oMail);
            return true;
        }
        catch (Exception err)
        {
            Response.Write(err.Message.ToString());
            return false;
        }
        finally
        {
            ////釋放資源
            oMail.Dispose();
        }

    }