This may point you in a useful direction:

use strict;
use warnings;

my %param =
  (
  fname1 => "Fred", lname1 => 'Bloggs', email1 => 'fred@xyzzy.com',
  fname2 => "Joe", lname2 => 'Bloggs', email2 => 'joe@plugh.com',
  fname3 => "Sue", lname3 => 'Brown', phone3 => '555-1234-567',
  fname4 => "", lname4 => 'Brown', phone4 => '555-1234-567',
  fname5 => "Liz", lname4 => 'Green',
  );
my @entries; 

for my $key (keys %param)
  {
  my ($field, $num) = $key =~ /^(.*?)(\d+)/;
  next if ! defined $num;
  ${$entries[--$num]}{$field} = $param{$key} || '';
  }

for my $entry (@entries)
  {
  next unless ($$entry{lname} && $$entry{fname}); # Must have a full n
+ame
  next unless ($$entry{phone} || $$entry{email}); # Must have phone or
+ email
  $$entry{phone} ||= '';
  $$entry{email} ||= '';
  print "$$entry{lname},$$entry{fname},$$entry{phone},$$entry{email}\n
+";
  }

[download]

Prints:

Bloggs,Fred,,fred@xyzzy.com
Bloggs,Joe,,joe@plugh.com
Brown,Sue,555-1234-567,

[download]

Update to get closer to OP's requested behaviour

DWIM is Perl's answer to Gödel

In reply to Re^3: retrieving similar form params by GrandFather
in thread retrieving similar form params by Anonymous Monk

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