SMTP mail rejected by firewall

[Glenn via .NET 247]

I setup asp.net web project to send mail. It works fine within my companies network. It sends mail ok to some of our clients, but some are rejected by the clients firewall. I noticed the header of a message sent by my asp.net app says

Received: from server-name (unknown[ip-address](misconfigured sender))

server-name and ip-address both have the correct values in them.

How can I get rid of unknown and misconfigured sender? I am sure this is why the firewall is rejecting the messages.

 

[David Lozzi]

In your script, are you specifying a SMTP server or just letting it using
its defaults?

David Lozzi