>>Which firewall did you turn off? You may have 2 firewalls, Windows and in your office router
>>Also your ISP may block port 25 to prevent outbound mail spam
>>
>
>Good thinking. I'd turned off the Windows firewall. As far as I can tell, my router has only an inbound firewall, not an outbound one.
>
>But your other idea got to me run a port checker and sure enough, port 25 is closed. So now I have to figure out if I can open it, and if not, what else I could do to test this code (since port 25 isn't essential to the project, just to the approach I was trying to use for testing).
>

Usually, ISP provide their own SMTP server when they block port 25.
Also, if you have business account, most likely you can ask them to unblock it