Need Help With new MTA Shell Calls (Postfix)

We sometimes send email notices for our users by doing an SQL query and then piping the email addresses to a shell script.

Under PLESK/Qmail the cmd looks like this:

"cat $Alert | /var/qmail/bin/qmail-inject RECIPIENT"

where $Alert contains the html email and "Recipient" is replaced on a repeat loop with a real@emailaddress.com

Now, we migrated to the new box under VirtualMin/WebMin and set the MTA to be Postfix...

Can anyone one help me re-write my shell cmd?