What error message are you getting? When you say you are manually Logged in as admin, does that mean you are manually logged in on the server or on your workstation?
It could be related to this:
In the services applet look at SQL Server Agent, at the Login in as. You want this to be a domain user -- who has a mail profile set up.
David Lundell
Principal Consultant and Trainer
www.mutuallybeneficial.com