error sending email in .NET

Question

i am getting an error saying "5.7.1: Unable to relay for [email protected]"

any ideas what this means?

Answer 1

Did you specify a SMTP server? Can we see some of your code?

Answer 2

The SMTP server has to be configured to relay mail to other domains.

Answer 3

It means that the SMTP server you are using doesn't allow relaying - this could be because you're not authenticating, or not sending to an email address that is local. There is an option (in IIS SMTP anyway) to allow relaying without authentication