Application Development Software

Hi,
I have a question about Beehive. I installed it and I'm trying to configure the email service.
At the moment I can receive emails from internet and send on the intranet, but I cannot sent email to internet.
I read on the Beehive documentation: http://download.oracle.com/docs/cd/E13789_01/bh.100/e13797/email.htm#BABHFDEC
"You can configure Oracle Beehive so that it acts as a relay server, accepting outbound e-mail messages from internal users, and forwarding them along to another SMTP service (such as Sendmail server, gateway, or an Internet Service Provider) for further processing."
So my question is: I can use relay server or I must use it.
In other words, can I user beehive to send email to internet without a relay service? or have I to use a sendmail or similar obligatory ?

Federico