When you send an email which will be blocked by a policy on the SMTP prevent server, you get an undelivery message (normal behaviour) without the correct VARIABLES.
Your message did not reach some or all of the intended recipients.
Subject: smtp prevent test
Sent: 8/18/2010 2:19 PM
The following recipient(s) could not be reached:
[email protected] on 8/18/2010 2:19 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<hostname.dlp.local #5.5.0 smtp;550-5.7.1 Dear $SENDER$, Your e-mail regarding "$SUBJECT$" was blocked from going to <font color="blue">$RECIPIENTS$</font> because it violated the company's <font color="blue">$POLICY$ </font> Policy.>
You can't use any VARIABLES in "BLOCK SMTP EMAIL response rule".
The VARIABLE is a custom attribute and it works only on the Enforce server. The SMTP blocking action is executed on the SMTP prevent server.
You can use the VARIABLES via notification response rule which gets executed on the Enforce server.