How to implements secure connections (No | SSL | STARTTLS) in SmtpClient to send mail?

Question

I use class SmtpClient of namespace System.Net.Mail to send mail: I create SmtpClient to send mail:

private static SmtpClient CreateSmtpClient (string host, string user, string password, int port)
        {
            var smtpClient = new SmtpClient (host, port);
            smtpClient.Credentials = new NetworkCredential (user, password);
            return smtpClient;
        }

and use it:

var mailMessage = new MailMessage ();
var smtpClient = CreateSmtpClient (host, user, password, port);
smtpClient.Send (mailMessage);

How to implements secure email transfer when I have 3 option secure connection is: No | STARTTLS | SSL ? Many thanks !

Solution

.NET built-in mail class doesn't support the needed SSL method (implicit SSL) and there's nothing to do with this: the reason is explained here.

There exist third-party SMTP client components that do both explicit and implicit SSL , for example, AIM(Aegis Implicit Mail), or you should consider sending email through Gmail, Yahoo, Outlook, etc.

Comments

[Evk]

For STARTTLS just do smtpClient.EnableSsl = true;

[Luke Le]

@Evk Thank for your reply. So SSL ? Do you have any suggestions for me?

[Evk]

If by SSL you mean connecting to 465 port (by default) - then it's not supported by SmtpClient.

[Luke Le]

@Evk, I got it. Thank for your support.

[Luke Le]

Thank for your reply. Maybe I will choose an exist third-party SMTP client components.

[N_E]

@maxchiu, how did you come accross microsoft dev blog in your search ? It's a very sound information.