(.NET Core C#) IMAP Download and Verify Signed (S/MIME) Email

Demonstrates how to download and verify digitally signed S/MIME email.

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

Chilkat.Imap imap = new Chilkat.Imap();

// Connect to an IMAP server.
// Use TLS
imap.Ssl = true;
imap.Port = 993;
bool success = imap.Connect("imap.someMailServer.com");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

success = imap.Login("myLogin","myPassword");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Select an IMAP mailbox
success = imap.SelectMailbox("Inbox");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// We can choose to fetch UIDs or sequence numbers.
bool fetchUids = true;

// Get the message IDs of all the emails in the mailbox
Chilkat.MessageSet messageSet = imap.Search("ALL",fetchUids);
if (imap.LastMethodSuccess != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Scan for emails with attachments, and save the attachments
// to a sub-directory.
int i = 0;
while (i < messageSet.Count) {

    string uid = messageSet.GetId(i);
    Debug.WriteLine("uid: " + uid);

    Chilkat.Email email = imap.FetchSingle(uid,true);

    // The security layers of signed and/or encrypted emails
    // are automatically "unwrapped" when loaded into
    // a Chilkat email object.
    // An application only needs to check to see if an email
    // was received signed or encrypted, and then examine
    // the success/failure.  For example:
    if (email.ReceivedSigned == true) {

        Debug.WriteLine("This email was signed.");

        // Check to see if the signatures were verified.
        if (email.SignaturesValid == true) {
            Debug.WriteLine("Digital signature(s) verified.");

            Debug.WriteLine("Signer: " + email.SignedBy);

            // The certificate used for signing may be obtained
            // by calling email.GetSignedByCert.
            Chilkat.Cert cert = email.GetSignedByCert();
            if (email.LastMethodSuccess != true) {
                Debug.WriteLine("Failed to get signing certificate object.");
            }
            else {
                Debug.WriteLine("Signing cert: " + cert.SubjectCN);

            }

        }
        else {
            Debug.WriteLine("Digital signature verification failed.");
        }

    }

    i = i + 1;
}

// Disconnect from the IMAP server.
success = imap.Disconnect();