(.NET Core C#) Bounced Email Handling

Demonstrates how to examine emails and detect which are bounced (automated) replies. Classifies each email according to the type of bounce.

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

Chilkat.Bounce bounce = new Chilkat.Bounce();

// The mailman object is used for receiving (POP3) 
// and sending (SMTP) email.
Chilkat.MailMan mailman = new Chilkat.MailMan();

// Set the POP3 server's hostname
mailman.MailHost = "mail.chilkatsoft.com";

// Set the POP3 login/password.
mailman.PopUsername = "myLogin";
mailman.PopPassword = "myPassword";

// Copy the all email from the user's POP3 mailbox 
// into a bundle object.  The email remains on the server.
// (There are other methods for deleting email from a POP3 server.)
Chilkat.EmailBundle bundle = mailman.CopyMail();
if (mailman.LastMethodSuccess == false) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

int i = 0;
Chilkat.Email email = null;
while (i < bundle.MessageCount) {
    email = bundle.GetEmail(i);

    bool success = bounce.ExamineEmail(email);
    if (success == false) {
        Debug.WriteLine(bounce.LastErrorText);

        return;
    }

    if (bounce.BounceType == 1) {
        // Hard bounce, log the email address
        Debug.WriteLine("Hard Bounce: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 2) {
        // Soft bounce, log the email address
        Debug.WriteLine("Soft Bounce: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 3) {
        // General bounce, no email address available.
        Debug.WriteLine("General Bounce: No email address");
    }

    if (bounce.BounceType == 4) {
        // General bounce, log the email address
        Debug.WriteLine("General Bounce: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 5) {
        // Mail blocked, log the email address
        // A bounce occured because the sender was blocked. 
        Debug.WriteLine("Mail Blocked: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 6) {
        // Auto-reply, log the email address
        Debug.WriteLine("Auto-Reply: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 7) {
        // Transient (recoverable) Failure, log the email address
        Debug.WriteLine("Transient Failure: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 8) {
        // Subscribe request, log the email address
        Debug.WriteLine("Subscribe Request: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 9) {
        // Unsubscribe Request, log the email address
        Debug.WriteLine("Unsubscribe Request: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 10) {
        // Virus Notification, log the email address
        Debug.WriteLine("Virus Notification: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 11) {
        // Suspected bounce.
        // This should be rare.  It indicates that the Bounce
        // component found strong evidence that this is a bounced
        // email, but couldn't quite recognize everything it
        // needed to be 100% sure.  Feel free to notify
        // support@chilkatsoft.com regarding emails having this
        // bounce type.
        Debug.WriteLine("Suspected Bounce!");
    }

    if (bounce.BounceType == 12) {
        // Challenge/Response - Auto-reply message sent by SPAM software 
        // where only verified email addresses are accepted. 
        Debug.WriteLine("Challenge: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 13) {
        // Address Change Notification Message.
        Debug.WriteLine("Address Change: " + bounce.BounceAddress);
    }

    if (bounce.BounceType == 14) {
        // Success DSN indicating that the message was successfully relayed.
        Debug.WriteLine("DSN Successful Relay: ");
    }

    i = i + 1;
}

success = mailman.Pop3EndSession();