If you create this outside of msdb, you have to use certificate based security to sign the activation stored procedure as explained in this article:
Using a Certificate Signed Stored Procedure to Execute sp_send_dbmail[/url]
As explained in the comments in the code, I create all this stuff in msdb so that we don't have to deal with managing cross database security and certificate signatures.
I am creating this within MSDB as stated in your following article:
http://www.sqlservercentral.com/articles/autogrowth/93229/
The ONLY difference is that I'm attempting to use an existing database during the Testing Event Notification instead of creating a new one.