(.NET Core C#) Send Signed Email using PFX File

Demonstrates how to send a signed email using a digital certificate w/ private key stored in a PFX file.

Chilkat .NET Downloads Chilkat .NET Assemblies Chilkat for .NET Core Chilkat for Mono

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

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

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

// 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 Admin <admin@chilkatsoft.com>";
bool success = email.AddTo("Chilkat Support","support@chilkatsoft.com");

// Indicate that the email should be sent signed.
email.SendSigned = true;

// Tell the mailman to use a PFX file as a source for locating
// the certificate and private key required for signing.
// The certificate chosen for signing will be the one that
// matches the sender's email address, which also has
// a private key.  All intermediate certs in the chain of 
// authentication, up to and including the root, will
// be included in the signature.
success = mailman.AddPfxSourceFile("/pfx_files/chilkatsoft_secret.pfx","secret");
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Signed email can be sent in two different ways.  
// In a multipart/signed email, the signature is attached as a separate MIME part.
// In an opaque email (signedData) the content of the email is encapsulated within the signature
// and the email is sent as "application/pkcs7-mime". 
// Either should be fine, but some receiving systems might require one or the other..
mailman.OpaqueSigning = false;

// Send a signed email.
success = mailman.SendEmail(email);
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
}
else {
    // The LastErrorText property provides information
    // even when successful.
    Debug.WriteLine(mailman.LastErrorText);
    Debug.WriteLine("Mail Sent!");
}