System.Net.Mail.MailMessage/System.Net.Mail.SmtpClient Sending Duplicate Emails

Question

The code below uses System.Net.Mail.MailMessage/System.Net.Mail.SmtpClient to email files from a ASP.NET/C# 3.5SP1 application running on IIS7 on Windows 2008R2. Even though we haven't changed the code in 3+ years, it has recently started sending duplicate emails. For example, if [email protected] is the currentVendor.Email, [email protected] receives 2 separate emails exactly the same. Any ideas? Would a Windows Update have caused this?

Vendor currentVendor = Vendor.GetCurrent();
string POLocation = Vendor.GetPOLocation();
    #if !DEBUG
                                    MailMessage mailer = new MailMessage("[email protected]", "[email protected]");
                                    string[] addresses = currentVendor.Email.Split(new char[] { ';', ',' });
                                    foreach (string recip in addresses)
                                    {
                                        mailer.To.Add(recip.Trim());
                                    }
    #else
                                MailMessage mailer = new MailMessage("[email protected]", "[email protected]");
    #endif
                                mailer.Subject = String.Format("{0} V2 Purchase Orders - {1}", currentVendor.Name, DateTime.Today.ToShortDateString());
                                mailer.IsBodyHtml = true;
                                mailer.Body = "Please find attached..... <br/>" +
                                              "This email is system generated. If you have any trouble please, contact us";
                                mailer.Attachments.Add(new Attachment(POLocation));

                                SmtpClient mailClient = new SmtpClient();
                                mailClient.Send(mailer);

Thanks in advance!

Answer 1

Try to check if this code:

Vendor currentVendor = Vendor.GetCurrent();

does not return duplicated email addresses?

There is only one call to MailClient.Send() method:

mailClient.Send(mailer);

But make sure you don't call the entire code snippet which you have pasted more than once!