Problem Solved. :)
I must use Routing Agent instead of SmtpReceive Agent because only Routing Agents are guaranteed to see all the Emails passing through Exchange Server.
Below is the modified working code, Everything else remains same
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Exchange.Data.Transport;
using Microsoft.Exchange.Data.Transport.Routing;
namespace MyAgents
{
public sealed class MyAgentFactory : RoutingAgentFactory
{
public override RoutingAgent CreateAgent(SmtpServer server)
{
return new MyAgent();
}
}
public class MyAgent : RoutingAgent
{
public MyAgent()
{
this.OnSubmittedMessage += new SubmittedMessageEventHandler(this.MySubmittedMessageHandler);
}
public void MySubmittedMessageHandler(SubmittedMessageEventSource source, QueuedMessageEventArgs e)
{
e.MailItem.Message.Subject = "This message passed through my agent: " + e.MailItem.Message.Subject;
}
}
}