I just realized it last night when I’m trying to send email using my office SMTP Server and it fails. Thinking that my server down, I checked the web site and its working fine. I’ll try sending the email again and it fails again. Suspected that the SMTP services may be down, I do a remote desktop to the server just to find out that the services is working fine. I even try to send a test email using the local computer and it working perfectly. So its my be on my end and not on the server end. Checkout my firewall and everything and its fine. And my suspicious goes to my internet provider which is Maxis Broadband who may be blocked port 25. To prove it, I do a telnet to my server and found out that it cannot be connected. Finally, I checked with Maxis web site and found out that they DID actually blocked port 25 since March 2010.
So now I need to change our office SMTP port to 587 as this port was slated for SMTP submission while port 25 was used for SMTP relay. And the easy way to do this are by using port forwarding in our router to do this as I don’t want to change to many things in my office intranet.