Send S/MIME Signed Email

Send digitally signed email using the digital certificate of the recipient. To successfully sign, the sender's certificate must be pre-installed with private key. Typically, this is done via a .pfx file, or through Internet Explorer. If your code is going to run within ASP, ASP.NET, or a Windows Service, you will need to follow the instructions here (http://blog.chilkatsoft.com/?p=149) to import your certificate w/ private key such that it is accessible by the calling process.

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Download Chilkat .NET for 1.0 / 1.1 Framework

//  The mailman object is used for sending and receiving email.
Chilkat.MailMan mailman = new Chilkat.MailMan();

//  Any string argument automatically begins the 30-day trial.
bool success;
success = mailman.UnlockComponent("30-day trial");
if (success != true) {
    MessageBox.Show("Component unlock failed");
    return;
}

//  Set the SMTP server.
mailman.SmtpHost = "smtp.chilkatsoft.com";

mailman.SmtpUsername = "myLogin";
mailman.SmtpPassword = "myPassword";

//  Create a new email object
Chilkat.Email email = new Chilkat.Email();

email.Subject = "This email is signed";
email.Body = "This is a digitally signed mail";
email.From = "Chilkat Support <admin@chilkatsoft.com>";
email.AddTo("Test","test@testemail.net");

//  In this example, we've already installed the certificate for "admin@chilkatsoft.com"
//  (with private key) in the current user's personal certificate store.
//  If the email.SendSigned property is set, Chilkat will
//  automatically search for and use the first non-expired certificate
//  matching the sender's email address.  Chilkat searches
//  the Current User's Personal certificate store, as well
//  as the Local Machine's Personal certificate store.
//  Run certmgr.msc to view the certs in the Current User's
//  certificate store.
email.SendSigned = true;

success = mailman.SendEmail(email);
if (success != true) {
    MessageBox.Show(mailman.LastErrorText);
}
else {
    MessageBox.Show(mailman.LastErrorText);
    MessageBox.Show("Mail Sent!");
}