How to identify a mail.is forwarded using java

In Java, you can identify a forwarded email using various techniques. Here are a few approaches:

Check the Received header: The Received header contains information about the email's journey, including any forwarding. You can parse this header to identify if the email was forwarded.

Example:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

//...

String emailContent = "";
try (BufferedReader reader = new BufferedReader(new InputStreamReader(new URL("https://mail.is/forwarded-email").openStream()))) {
    String line;
    while ((line = reader.readLine())!= null) {
        emailContent += line + "\n";
    }
}

Pattern pattern = Pattern.compile("Received: (.*?)(?:from|by)");
Matcher matcher = pattern.matcher(emailContent);
if (matcher.find()) {
    String receivedHeader = matcher.group(1);
    if (receivedHeader.contains("via")) {
        System.out.println("Email was forwarded!");
    }
}

In this example, we use a regular expression to extract the Received header and check if it contains the string "via", which is often a sign of forwarding.

Check the X-Forwarded-From header: Some email servers add an X-Forwarded-From header when forwarding an email. You can check for this header to identify forwarding.

Example:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;

//...

String emailContent = "";
try (BufferedReader reader = new BufferedReader(new InputStreamReader(new URL("https://mail.is/forwarded-email").openStream()))) {
    String line;
    while ((line = reader.readLine())!= null) {
        emailContent += line + "\n";
    }
}

Pattern pattern = Pattern.compile("X-Forwarded-From: (.*?)(?:\\s|$)");
Matcher matcher = pattern.matcher(emailContent);
if (matcher.find()) {
    System.out.println("Email was forwarded!");
}

In this example, we use a regular expression to extract the X-Forwarded-From header and check if it's present.

Check the email's Message-ID: If the email's Message-ID has changed, it may indicate that the email was forwarded.

Example:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;

//...

String emailContent = "";
try (BufferedReader reader = new BufferedReader(new InputStreamReader(new URL("https://mail.is/forwarded-email").openStream()))) {
    String line;
    while ((line = reader.readLine())!= null) {
        emailContent += line + "\n";
    }
}

Pattern pattern = Pattern.compile("Message-ID: (.*?)(?:\\s|$)");
Matcher matcher = pattern.matcher(emailContent);
if (matcher.find()) {
    String messageId = matcher.group(1);
    // Check if the Message-ID has changed
    if (!messageId.equals(originalMessageId)) {
        System.out.println("Email was forwarded!");
    }
}

In this example, we extract the Message-ID and compare it to the original Message-ID to detect forwarding.

Use a dedicated email parsing library: There are libraries like JavaMail or Apache James that provide more advanced email parsing capabilities, including detection of forwarded emails.

Remember that these approaches may not work for all emails, as forwarding mechanisms can vary. Additionally, some emails may be forwarded without leaving any obvious signs.

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How to identify a mail.is forwarded using java