Error "A recipient must be specified" occurred while sending mail in c#

Question

I am trying to send mail with multiple attachment in c# but I am getting this error

A recipient must be specified while sending mail

Here is my code for sending mail with attachment

            string to = txtto.Text; //To address        
            string from = "xxx@mail.com"; //From address     

            MailMessage message = new MailMessage();
            message.From = new MailAddress(from);


            if (fileuploading.HasFile)//Attaching document    
            {
                string FileNamess = fileuploading.PostedFile.FileName;
                string FileName = Path.GetFileName(fileuploading.PostedFile.FileName);


                message.Attachments.Add(new System.Net.Mail.Attachment(fileuploading.PostedFile.InputStream,FileName));

            }

            string mailbody = editor.Text;
            message.Subject = txtsubject.Text;
            message.Body = mailbody;
            message.BodyEncoding = Encoding.UTF8;
            message.IsBodyHtml = true;


            SmtpClient client = new SmtpClient("smtp.gmail.com", 587); //Gmail smtp        
            System.Net.NetworkCredential basicCredential1 = new
            System.Net.NetworkCredential("xxx@mail.com","xxxxx");
            client.EnableSsl = true;
            client.UseDefaultCredentials = false;
            client.Credentials = basicCredential1;

            try
            {
                client.Send(message);
            }

            catch (Exception ex)
            {
                throw ex;
            }

Answer 1

You have an unused string "to". You need to add this string to recipient list message.To.

To do that refer following snippet;

string to = txtto.Text; //To address        
string from = "xxx@mail.com"; //From address     

MailMessage message = new MailMessage();
message.From = new MailAddress(from);
message.To.Add(to);     //Add this line to your code

For above example to work, your string to should contain a recipient address in format "xxx@mail.com".