re email alerts on Macintosh

Hello

We have xymon installed on a Macintosh running 10.6.8.
We have configured the alerts conf file as follows;
HOST=%(help|host|jumpmail|wilma|portal).jumpit.ca SERVICE=http
        MAIL (email address)@jumpit.ca REPEAT=20 RECOVERED

When an alert is triggered, no email is being sent out.

I can however send an email from the host command line as follows;
sh-3.2# mail (email address)@jumpit.ca
Subject: test
test message
.
EOT
sh-3.2#