SMTP Relay And CDO?

I have installed IIS on my local machine. The SMTP is setup to then relay the messages through a remote smtp server. If I just drop email text files in the pickup directory it works fine. However, in my application, creating the same email message returns the following error:

The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for xxx@xxx.com

(obviously I've blanked out the email address)

The same code works fine if I set it up to send it to the remote server directly but we don't want to do this.

I solved this myself and thougt I would update the thread. I then tried using Outlook Express and got the same error. This made me realise it must be a problem with the settings of my local SMTP server rather than a coding issue.

It turns out it was. In the SMTP server settings on the Access tab I need to add 127.0.0.1 to the granted relay restrictions. Then it allows mail through from both Outlook Express on my machine and my app.