Solved: Invalid character @ error in my mail script. What is wrong with the Script ( ASP.NET C#)

I keep getting the following error when I run this code. what is wrong with the code.

Error:
An invalid character was found in the mail header: '@'.

string bmsg = "<h3>" + txtFirstName.Text + " " + txtLastName.Text + "</h3>";
            bmsg += "<p>This is your EPIC IPCST Conference Ticket Number &nbsp;<strong>" + lbInvoiceNumber.Text + "</strong>&nbsp; please keep this for your records";

            string pt = "mypw";
            [b]string cr = "my@domain.com";[/b]
            MailMessage mm = new MailMessage(cr, emc);


            mm.Subject = "2015 Conference Ticket";
            mm.Body = bmsg;

            mm.IsBodyHtml = true;
            SmtpClient smtp = new SmtpClient();
            smtp.Host = "smtpout.secureserver.net";
            smtp.EnableSsl = false;
            NetworkCredential NetworkCred = new NetworkCredential(cr, pt);
            smtp.UseDefaultCredentials = true;
            smtp.Credentials = NetworkCred;
            smtp.Port = 80;
            smtp.Send(mm);

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ERROR:
An invalid character was found in the mail header: '@'.

Line 401 is where the error is coming form.
string cr = "my@domain.com";

Stack:

Line 400:            string pt = "mypw";
Line 401:            string cr = "my@domain.com";
Line 402:            MailMessage mm = new MailMessage(cr, emc);

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Thank you.