Mailing list without SQL

Hi...
This is my first try for writing my OWN tutorial.
So, I'll write a PERL script for a mailing list, without SQL or any other database.

Code:

---

#!/usr/bin/perl -w
# put above path to your perl interpreter

$dbDir = '.';
# directory where you want to save data
$dbFile = 'maillist.dat';
# put above file where you want to save data...
$mailProgie = '/usr/sbin/sendmail';
# put above path to your sendmail progie
$adminEmail = 'whatever@addy.com';
# put above administrator's mail
$adminName = 'Whatever Name';
# put above administrator's name

use CGI;
$req = new CGI;
$action = $req->param("action");

if ($action eq "sign") {
&checkIfExists;
&writeData;
} elsif ($action eq "send") {
&sendEmail
} else {
$errorData = "Invalid action!";
&errorSub;
}

sub checkIfExists {
$uEmail = $req->param("email");
$uName = $req->param("name");
$uAddy = $req->param("url");
open(FILE,"<$dbDir/$dbFile");
@dataFile = <FILE>;
close(FILE);
foreach $dataFile (@dataFile) {
if ($dataFile =~ /$uEmail/) {
$errorData = "Email exists!";
&errorSub;
      }
  }
}

sub errorSub {
print "Content-type: text/plain\n\n";
print "&ret=true&error=$errorData&";
exit;
}

sub writeData {
open(FILE,">>$dbDir/$dbFile");
print FILE "¦¦$uEmail¦$uName¦$uAddy";
close(FILE);
print "Content-type: text/plain\n\n";
print "&ret=true&";
}

sub sendEmail {
$getSubject = $req->param("subject");
$getMessage = $req->param("message");
open(FILE,"<$dbDir/$dbFile");
@dataFile = split(/¦¦/,<FILE>);
close(FILE);
foreach $dataFile (@dataFile) {
my @tempData = split(/¦/,$dataFile);
open MAIL, "|$mailProgie -t -i" || die "open: $!";
print MAIL "To: $tempData[0]($tempData[1])\n";
print MAIL "From: $adminEmail($adminName)\n";
print MAIL "Subject: $getSubject\n";
print MAIL "Content-type: text/html\n\n";
# print MAIL "Content-type: text/plain\n\n"; if you will use text/plain
print MAIL "$getMessage\n";
close MAIL;
}
print "&ret=true&";
}

---

I'll assume that all who read this tutorial know where to put this .pl file and how to make a form to send data to it.
So, that's it for my tutorial.
Please tell me on how i can improve it or if it has been posted before.
Thanks. :D

Good tut on perl.I like it when I see more people posting in perl.

Thanks :D