Cannot send email from asp.net membership API!!!

I can send email from the website using web form, but cannot send via ASP.NET membership API- The password retrieval function. The error message I got is "Mailbox unavailable. The server response was: <email address> No such user here . Any idea?

Thanks

 

It doesn't sound like the SMTP authentication is being passed correctly in your ASP.Net application. Typically when you send email via system.net.mail, you define it in the applications web.config file. You may want to check that to make sure SMTP authentication is being passed correctly.