How to break the email thread while subject change

You can also set the modifiedSubject value as the subject line of the email when sending the email using your email client or library.

To break an email thread or chain, you can modify the subject line of the email. When an email client receives an email with a different subject line, it typically treats it as a new email thread. In your case, you can modify the subject line of the reply email with a unique identifier or text that is different from the original email's subject line.

using System.Text.RegularExpressions;

string originalSubject = "RE: Your subject";
string newSubject = "RE: Your subject [NEW THREAD]";
string modifiedSubject = Regex.Replace(originalSubject, "^RE:", newSubject);

In the above example, the originalSubject variable contains the subject line of the reply email. The newSubject variable contains the modified subject line with the unique identifier. The modifiedSubject variable contains the final subject line with the newSubject text replacing the RE: prefix.

I have a thread with multiple messages i want to break the thread when subject of recevied email is changed as new thread.

using System.Net.Mail;

// Detect subject change
if (receivedEmail.Subject != originalEmail.Subject)
{
    // Create a new email message
    MailMessage newEmail = new MailMessage();

    // Set the new subject
    newEmail.Subject = receivedEmail.Subject;

    // Add the recipient
    newEmail.To.Add(receivedEmail.To.ToString());

    // Add the body
    newEmail.Body = receivedEmail.Body;

    // Send the email
    SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
    smtpClient.EnableSsl = true;
    smtpClient.Credentials = new System.Net.NetworkCredential("[email protected]", "your_password");
    smtpClient.Send(newEmail);
}