I'm not sure if this is what you were talking about. but it's my guess. This is not a complete script, you need to add the end messages.

It will basicaly assign the email address with an ID and then stores that info in a flat file database. Then when the user clicks the link from the email, the script will check the info from the link with the info in the db and check for a match.

#!/usr/bin/perl
#
# evs.pl
#

    # use the CGI mod
    use CGI;
    use Email::Valid;

    # new CGI
    my $CGI = CGI->new();

    # define variables
    my $cmd = $CGI->param('cmd');
    my $account = $CGI->param('account');
    my $email = $CGI->param('email');

    if ($cmd eq "activate") {
        &activate;        # activate the account
    }
    else {
        &verify;            # verify the email address and send email
    }

    # exit
    exit;

# Verify
sub verify { 

    # make sure an email was entered
    if ( ! $email ) {    
        &error(" No Email Address was entered! ");
    }
    
    # make sure it is a vaid email address
    if ( ! Email::Valid->address($email) ) {
        &error(" An invalid Email Address was entered! ");
    }

    # Get a new account ID
    open(FILE, "id.txt") || error("No ID file");        # Make sure yo
+u change the path
    my $ID = <FILE>;
    close(FILE);

    # Increase the ID by one
    $ID++;

    # Rewrite the ID file
    open(FILE, ">id.txt") || error("Can't write ID File");
    print FILE $ID;
    close(FILE);

    # Add this email to the 
    # email db
    open(DB, ">>email_db.txt") || error("Could not write to DB");
    print DB "$ID|$email|0";        # The 0 is a status flag showing
    close(DB);            # that the email address is not activated

    # Send them an email with
    # the link and new ID.
    # I don't know what email server
    # you're useing but I assume you do.
    # The link you need will be
    # www.page.com/evs/evs.pl?cmd=activate&account=$ID&email=$email

    # then finish with a message
    # to the user.
    # ...

    exit;
}

# Activate
sub activate {

    # Make sure they included
    # an account ID and Email Address
    if ( ! $account || ! $email ) {
        &error(" An Account ID or Email Address was not included ");
    }

    # Open the db
    open(DB, "email_db.txt") || error("Could not open Email DB");
    my @emailDB = <DB>;
    close(DB);

    # keep the db
    my @keepDB = ();
    
    # found flag
    my $found = 0;

    foreach (@emailDB) {
        chomp($_);
        my ($db_ID, $db_email, $db_status) = split(/\|/, $_);

        # Match the email
        if ($db_email eq $email) {

            $found = 1;            # We have found the Email    
        
            # Check to match the ID
            if ($db_ID eq $account) {
                $found = 2;        # Email found and ID matches
            }

        }
        else {
            push (@keepDB, $_);        # Return to db if it's not the 
+email
        }
    }

    # Check for some errors
    if ($found == 0) {
        &error(" Email Address not in our Database! ");
    }
    elsif ($found == 1) {
        &error(" The Account ID was incorrect! ");
    }

    # ReWrite the db to show the this Email
    # Address has been been activated
    open(FILE, ">email_db.txt") || error("Could not write email db");
    print FILE "$ID|$email|1\n";
    foreach (@keepDB) { print FILE "$_\n"; }
    close(FILE);

    # Now you can finish the program
    # as you wish.

    exit;

}

# Errors
sub error { 

    # get the error message
    my($error_msg) = @_;

    # print the page header
    print $CGI-header();

    # print the error
    print $error_msg;

    exit;

}
[download]

If anyone has any suggestions about the script please let me know. I'm somewhat new to perl and could use some constructive criticism about my programming.

Update: Error checking with open, my instead of local, == instead of eq