sweetblood,
Try the following untested code:

#!/usr/bin/perl -w
use strict;

my %rets;

open(RL, "/home/myftplog") or die "Unable to open input file : $!"

my @fields = qw (
    FNAME RECLEN LIAISON_EMAIL LIAISON_FNAME
    LIAISON_LNAME LIAISON_AREACODE LIAISON_PHONE
    LIAISON2_EMAIL LIAISON2_FNAME LIAISON2_LNAME
    LIAISON2_PHONE RETNAME RETAILER_EMAIL
    LIAISON2_AREACODE RETAILER2_EMAIL FTPCHECK
    RETID SCRIPT_NAME EXECFLAG FREQUENCY FILE_NUMBER
);

while (<RL>) {
    chomp;
    next if /^$/;
    my @vals = split /:/;
    $vals[0] ||= '_001';
    my %temp_hash;
    @temp_hash{ @fields } = @vals;
    $hash{ $vals[0] } = \%temp_hash;
}

print $_, $/ for keys %rets;
[download]

Cheers - L~R