if (fork == 0) { # create a subprocess
 local $SIG{HUP} = sub {}; # ignore SIGHUP (untested)
 close STDIN; # daemonize
 close STDOUT;
 open STDOUT,">/dev/null" || die $!;
 close STDERR;
 open STDERR,">/dev/null" || die $!;
 # do anything
 open(MAIL, "|/usr/sbin/sendmail -t");  
 ## Mail Header 
 print MAIL "To: $to\n"; 
 print MAIL "From: $from\n";
 print MAIL "Subject: $subject\n\n"; 
 ## Mail Body 
 print MAIL "write your mail body text here\n";   
 close(MAIL);
 exit(0);
}