System.Net.Mail Error: Unable to read data from the transport connection: net_io_connectionclosed

[nate.strules]

I've looked everywhere for an answer to this, but only a few people
seem to have encountered it.

The code is straightforward:

MailMessage mail = new MailMessage(from, to, subject, body);
SmtpClient client = new SmtpClient("localhost");
client.Send (mail);

The code works fine on my development machine (XP Pro). When moved to
staging (2003 Server), I get the "connection closed" error. I've
confirmed the following:

-- "localhost" resolves to 127.0.0.1 (also tried using the loopback
address with the same error)
-- SMTP service is running on port 25
-- service is configured to relay mail
-- another app (Community Server) is using the service to send email
without any problems.

I'm at wit's end

TIA

 

[nate.strules]

As usual, this problem was resolved out not long after posting this
message. The problem was how the SMTP service was set up.
Specifically, the service has been bound to a specific IP address (not
the webserver's; see the "IP Address" dropdown in the "General" tab).
Once this was set to "(All Unassigned)". Everything worked fine.
Hopefully this message will save someone the hours of aggravation I
endured.