winform 使用SMTP发送带附件的邮件，发送成功后附件提示正在被使用

原始牛 2014-04-21 04:18:55

大家好，最近我在改一个自动发邮件的程序，本以为很快就能做好，直到测试的时候才发现有个问题。邮件在发送成功后，双击附件时就提示文件正在被另外一个程序占用。
下面是我发送邮件的代码：



//MailQueue 是我做的一个队列 里面包含发送邮件所需要的 收件人 CC 主题 邮件内容 以及附件所在的位置。

MailQueue mlq = mlqueue.GetMailQueue();

            //while mail recipients is blank , we will execute this job. 

            try

            {

                if (mlq.Mail_to != "")

                {

                    //MailAddress mailto;

                    //MailAddress mailcc;



                    System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(strMailserver);

                    client.UseDefaultCredentials = false;

                    client.Credentials = new System.Net.NetworkCredential(strMailaddress, strMailpwd);

                    client.DeliveryMethod = SmtpDeliveryMethod.Network;



                    System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();

                    if (!File.Exists(mlq.Mail_attach))

                    {

                        message.To.Add(new MailAddress(mlq.Mail_admin));

                        mlq.Mail_subject = mlq.Mail_taskname + "   未发现邮件附件。";

                    }

                    else

                    {

//我的邮件接收人是以;隔开的

                        string[] mailtoarr;

                        mailtoarr = mlq.Mail_to.Split(';');

                        for (int i = 0; i < mailtoarr.Length; i++)

                        {

                            if (mailtoarr[i] != "")

                                message.To.Add(new MailAddress(mailtoarr[i]));

                        }



                        string[] mailccarr;

                        mailccarr = mlq.Mail_cc.Split(';');

                        for (int i = 0; i < mailccarr.Length; i++)

                        {

                            if (mailccarr[i] != "")

                                message.CC.Add(new MailAddress(mailccarr[i]));

                        }



                    }

                    MailAddress from = new MailAddress(strMailaddress, "ReportMachine/ISD");

                    message.Priority = MailPriority.Normal;

                    message.From = from;

                    message.Subject = mlq.Mail_subject;

                    message.Body = mlq.Mail_body;

                    message.IsBodyHtml = true;



                    System.Net.Mail.Attachment attachment = new System.Net.Mail.Attachment(mlq.Mail_attach);

                    message.Attachments.Add(attachment);

                    message.BodyEncoding = System.Text.Encoding.UTF8;

                    message.IsBodyHtml = true;

                    client.Send(message);



                    writelog(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " 邮件发送成功!任务名称:" + mlq.Mail_taskname);

                    //Thread.Sleep(5000);

                    //if (File.Exists(mlq.Mail_attach))

                    //    File.Delete(mlq.Mail_attach);

                }

            }

            catch (Exception err)

            {

                writelog(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " 邮件发送失败!任务名称:" + mlq.Mail_taskname + " [错误代码]" + err.Message);

            }