Went through your study material and found two ways to get list of rejected recipients,if any when email is sent using Rebex Smtp.
1) Using Rebex.Net.Smtp.SendDirect() ;
SmtpRejectedRecipient rejected = Rebex.Net.Smtp.SendDirect(MailMessage);
MessageBox.Show("Rejected Recipients count: " + rejected.Count());
2) Using RejectedRecipient event
smtpObject.RejectedRecipient += smtpObject_RejectedRecipient;
private void smtpObject_RejectedRecipient(object sender, SmtpRejectedRecipientEventArgs e)
Did implement both with rebex latest dlls. Could not get rejected recipients list. Does rebex Smtp support giving list of rejected recipients?