send email with smtp client in c#

Question

I need to send emails from my Asp.net c# site, we are hosting on ovh, here what I did:

public static void Send(string stringFrom, string stringFromPass, 
        string stringTo, string stringBody, string stringSubject, int tryNb)
    {
        // Command line argument must the the SMTP host.
        SmtpClient client = new SmtpClient("smtp.mondomaine.me", 587);
        // Specify the e-mail sender. 
        // Create a mailing address that includes a UTF8 character 
        // in the display name.
        MailAddress from = new MailAddress(stringFrom,
           "Sender",
        System.Text.Encoding.UTF8);
        // Set destinations for the e-mail message.
        MailAddress to = new MailAddress(stringTo);
        // Specify the message content.
        MailMessage message = new MailMessage(from, to);
        message.Body = stringBody;
        message.IsBodyHtml = true;
        message.BodyEncoding = System.Text.Encoding.UTF8;
        message.Subject = stringSubject;
        message.SubjectEncoding = System.Text.Encoding.UTF8;
        //provide Authentication Details need to be passed when sending email from gmail
        string password = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(stringFromPass));
        NetworkCredential mailAuthentication = new NetworkCredential(stringFrom, password);
        client.UseDefaultCredentials = false;
        client.Credentials = mailAuthentication; 
        // Set the method that is called back when the send operation ends.
        client.SendCompleted += new
        SendCompletedEventHandler(SendCompletedCallback);
        // The userState can be any object that allows your callback  
        // method to identify this send operation. 
        // For this example, the userToken is a string constant. 
        string userState = stringFrom + "*&(k)&*" +
            stringFromPass + "*&(k)&*" + stringTo + "*&(k)&*" +
            stringBody + "*&(k)&*" + stringSubject + "*&(k)&*" + tryNb.ToString();
        client.SendAsync(message, userState);
    }

and then i'm calling this fonction whenever i need to. I'm receiving an ovh server response:

sorry, invalid MAIL FROM for open-smtp session (http://travaux.ovh.com/?do=details&id=2602)

on this last link they told that:

messages sent via open-smtp will only be accepted if the email address of the fields From / Sender is the same connection login used for POP access.

As you see in my code i'm not using POP and i dont know how to. so why this restriction ? Any idea how to fix that will be much apreciated.

Answer 1

the problem was caused by the mailAuthentication, now i'm using System.Security.SecureString instead of Convert.ToBase64String to encode passwords and everything work well.

System.Security.SecureString secureString = new System.Security.SecureString();
stringFromPass.ToCharArray().ToList().ForEach(p => secureString.AppendChar(p));
NetworkCredential mailAuthentication = new NetworkCredential(stringFrom, secureString);

In outlook, you must configure your smtp to use email and password

Answer 2

If you want to send throw Gmail-Id.

---

In your Email ID change the Email-setting

Follow these step

• Click 1 --> Setting

• Click 2 --> Forwarding and POP/IMAP

• Clect 3 --> Enable IMAP Access

---

Mailing function:

MailMessage message = new MailMessage();
message.From = new MailAddress("Abc@Servername.com");
message.To.Add("Tosender@Servername.com");
message.Subject = "Your QR Code Image";
message.Body = "Please open this link and download this QR Code image for scanning your QRCode :" + QR_Code;

SmtpClient client = new SmtpClient();
client.EnableSsl = true;
client.Send(message);

In WebConfig:

<system.net>
    <mailSettings>
        <smtp deliveryMethod="Network">
            <network host="smtp.gmail.com" port="587" userName="abc@gmail.com" password="****" />
        </smtp>
    </mailSettings>
</system.net>