I want to configure SMTP on my web server, so that any email sent through the SMTP server is relayed to a remote SMTP Server. The IIS SMTP server would have to use SMTP authentication, and use the host name, username and password (as if configuring a normal email client).
Does anybody know if this is possible?
Yes, it' completely possible, and relatively easy to configure.
I've got a couple of articles about SmartHosting on my web site that will probably help:
http://www.christopherlewis.com/SmartHosting/SMTPSmartHosting.htm
and
http://www.christopherlewis.com/SmartHosting/SMTPSmartHostingPt2.htm
They're written towards Exchange 2003, but Exchange 2003 used IIS's SMTP engine, so the settings are the same.
Bascially, you right click the SMTP site, select properties, Delivery tab, Outbound security, and enter your credientials in the Basic Authentication fields. Back on the Delivery tab, you then click Advanced and enter the remote SMTP server name in the SmartHost field.
Editing
The links above are no longer available.
Try http://intellitect.com/configuring-windows-smtp-server-on-windows-2008-for-relay/.
HTH and answers your needs
http://www.cmsconnect.com/praetor/webhelpg2/Chapter_2_-_Pre-installation_considerations/Configuring_the_SMTP_Server.htm
I think you can only set outbound relays for specific domains, not blanket coverage.
http://www.isaserver.org/articles/smtprelayinboundoutbound.html
EDIT:
I've not done this before, buy maybe worth a try:
From the Server properties, you could try selelcting the 'Delivery' Tab, then advanced. In the Smart Host, type the outgoing SMTP relay IP / domain. Select OK, and then select 'Outboud Security' and enter your username / password in the basic authentication box.