On the otn forum, I have seen a number of posts about users trying to send emails from the database. For those that don't know it yet, there is the utl_smtp package that can be used for this purpose.
Setup is very easy and usage is quite straightforward. Either use a procedure or a function and make use of the basic commands (smtp connection, message setup, message sending and smtp deconnect). If you need to send UTF characters, you will have to use the raw command.
For further info, check:
www.oracle.com/technology/sample_code/
UTL_SMTP package for sending emails