I have a problem with sending email from internal IIS smtp server to internal users though exchange server.
We have a domain with Exchange 2007/windows2008, DC/Windows2008 and IIS/Windows2008 servers and around 15 PCs.
The IIS/Windows2008 has a custom app which creates an application form and will send to exchange and users will receive. this is all happening internally.
The problem is the IIS can send email to external address (e.g gmail, yahoo) but can't send to internal address and just sits in qurere folder.so as workaround we are sending email to external address and it autoforwards to our email address but I want to avoid to do this.
It looked very similar to link below and I enabled smart host and added mx record on DNS but sill no luck. I can confirm that port 25 is opened from IIS to exchange.
(Virtual SMTP Server - IIS 5.0 - Can't send to internal domain through local Exch 2003 server)