I downloaded the “Send Mail” VB10 sample from the Visual Basic 2010 Samples web pang and installed IIS (Internet Information Services 5.1) on my Windows XP Pro SP3 laptop. I was able to use the send mail sample instantly and went on to develop a more tailored program for sending mail. It all works great! However, when I take my laptop to different wifi network, with a different ISP (AT&T), something changes. My program still “seems” to work – it even gives me the “Mail Sent Successfully” message, but no mail makes it to it’s destination. Upon further investigation, I found that the outbound mail messages were accumulating in a folder called C:\Inetpub\mailroot\Queue.
What is causing this? Can I reconfigure something on IIS or within my VB10 program to make it work on AT&T? I have tried dozens of suggestions, but nothing has worked. I developed my program for the purpose of using it on the AT&T network – I need to have automated messages sent to me from that (AT&T) location. Can anybody help?
You need to setup IIS to forward the emails to your ISP so they can go out to the wide world.
Perhaps this KB article can help.
Also, see this ServerFault thread.