feat: add SMTP server and mail sender scripts

Implement an SMTP server using aiosmtpd and a mail sender script. The 
server handles incoming messages and prints their content, while the 
mail sender constructs and sends an email message. These changes 
enable local email testing for the CNP assignment, improving 
development efficiency.

CNP/Wireshark/SMTP/mail-sender.py

@@ -0,0 +1,14 @@
+import smtplib
+from email.message import EmailMessage
+
+# the email message
+msg = EmailMessage()
+msg['Subject'] = 'CNP Assignment Email'
+msg['From'] = 'aadit@example.com'
+msg['To'] = 'shreyas@example.com' # used example.com just to not have a DNS error.
+msg.set_content('Hello World. This is a message that is to be captured for the CNP FISAC II.')
+
+#SMTP server running on localhost on port 25
+with smtplib.SMTP('127.0.0.1', 25) as server:
+    server.set_debuglevel(1)  # debug output to see the SMTP conversation (for dev log)
+    server.send_message(msg)

CNP/Wireshark/SMTP/smtp-server.py

@@ -0,0 +1,33 @@
+import asyncio
+import uvloop
+from aiosmtpd.controller import Controller
+
+# handler that just prints the message content
+class PrintHandler:
+    async def handle_DATA(self, server, session, envelope):
+        print("Message from:", envelope.mail_from)
+        print("Recipients:", envelope.rcpt_tos)
+        print("Message data:")
+        print(envelope.content.decode('utf8', errors='replace'))
+        print("End of message")
+        # Respond with a success code
+        return '250 Message accepted for delivery'
+
+# uvloop for better performance
+asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
+
+def run_server():
+    # SMTP server controller, binding to localhost on port 25
+    controller = Controller(PrintHandler(), hostname='127.0.0.1', port=25)
+    controller.start()
+    print("SMTP server running on port 25. Press Ctrl+C to stop.")
+    try:
+        # Run forever
+        asyncio.get_event_loop().run_forever()
+    except KeyboardInterrupt:
+        pass
+    finally:
+        controller.stop()
+
+if __name__ == '__main__':
+    run_server()