I thought this simple solution could perhaps fit your needs.
As for any other type library, you can reference the library and use Outlook
but you'll have generally some more details to deal with (generally security
issues). Pay attention also to low probability conditions that could arise
over time (for example if you exceed the allowed space for the mailbox you
are using, you won't be able to send a message : for this reason you may
have to tweak the mailbox config to make sure it is not configured to keep
sent mails etc...). Also don't know for Outlook but an app such as Excel or
Word can also sometimes raises dialog boxes. Of course you must code around
this to avoid having the application being "stopped" server side.
For all these reasons, I weight carefully the advantage before running an
end user application server side.
My second choice would be CDO
(
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnanchor/h
tml/messagingcollaboration.asp) and using Outlook server side would be my
last resort.
Patrice