error sending email in .NET

Question

i am getting an error saying "5.7.1: Unable to relay for xxx@gmail.com"

any ideas what this means?

Answer 1

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

Answer 2

SMTP服务器必须配置为将邮件中继到其他域。

Answer 3

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