ASP.Net - sending SMTP mail via IIS 7.5 SMTP Server

I have recently configured IIS 7.5 to use the SMTP server. Now, I have my ASP .Net application that was running in IIS 6 fine, moved over to IIS 7.5. The website had email functionality, but thi开发者_运维问答s has no stopped working. Has anyone else managed to get IIS 7.5 SMTP working with ASP.Net?

EDIT: The website is load balanced, would this make a difference?

http://forums.iis.net/t/1157046.aspx

Hope that helps.

Have found the solution. Basically, after stressing out over this for 2 days, it was to do with the Relay configuration. Added in the necessary IP addresses and it is now working.