Hi,
You will have to allow relaying from the IP address of where the ASP.NET app resides.

>I am having a problem with a ASP.NET application (but it really does not matter if it is ASP.NET or VFP or whatever) sending email message. I think in order to solve the problem I need to understand how SMTP relaying works. Here is a brief description of the problem (I had this message in .net forum so sorry for the repeat):
>
>The application knows the IP address of the Exchange Server. The application resides on web server where IIS is running. OS is Win 2000.
>The application send two emails (at once) using SmtpMail class (of .NET framework). One email goes to a person in the organization. And at the same time another email to a text pager. The email to the person gets delivered ok. The second one, that has to go to the text pager gets error:
>
>

>The server rejected one or more recipient addresses. The server
>response was: 550 5.7.1 Unable to relay for
>3132@amcomdb1.hospitalname.org
>

>
>First, can someone help me understand the following. Do both of my messages (the one to an employee and the one to the text pager) go through the same Exchange Server?
>
>Second, the above error message refers to "server". Would that be Exchange Server or web server?
>
>Third. I found the following suggestion to the "unable to relay" problem:
>
>

>If you are using the IIS SMTP Service try allowing relaying for
>your IP address by:
>Opening the IIS Admin MMC
>Right-Clicking on the SMTP Virtual Server and selecting Properties
>On the Access tab, click the Relay button
>Grant 127.0.0.1 (or the IP address used by System.Web.Mail) to the
>Computers list.
>Close all dialogs
>Restarting the SMTP Service
>

>
>In the above, what IP would I tell my customer to add in place where it says "Grant 127.0.0.1"?
>
>Any other suggestions or clarifications would be greatly appreciated.
>Thank you.