Must Restart syslog-ng to send email

Dear friends
I'm using Syslog-ng v 3 installed in RHEL 5
           I have a small problem with my syslog-ng configuration, I'm trying to filter logs from a log file and forwerd it to perl script to send it by email,
This part of  configuration like the following:
=====================================================
source sme {file (/var/log/syslog-ng/servers/172.31.250.68/local7.log); };

destination maillog { program ("/usr/local/bin/syslog-mail-perl" );
 };
log {source(sme); destination(maillog); };
=====================================================

And the perl script like the following:
+++++++++++++++++++++++++++++++++++=
#!/usr/bin/perl -n
# thanks to Brian Dowling for an example with security in mind.

$TO = 'root';
$FROM = $TO;

s/^//;

open(MAIL, "|/usr/sbin/sendmail -t");

print MAIL "EOT";
To: $TO
From: $FROM
Subject: SME Log Alert: $_

$_

EOT

close(MAIL);
+++++++++++++++++++++++++++++++++++++++

I found that I must restart syslog every time to send the mails , In another word it buffer the emails tell I restart syslog-ng then It forwerd it to send mail and can see it in the mail log.
Do you have any idea for that ?
Thanks