OK, Maybe it's the DB admin in me but why not this:

my %Emails = ( 'Name 1' => 'Some1@somewhere.com',
  'Name 2' => 'Some2@whereelse.com',
  'Name 3' => 'Some3@nowhere.com',
  'Name 4' => 'Some4@someelse.com',
  'Category1' => [ 'Name 1', 'Name 2' ],
  'Category2' => [ 'Name 2', 'Name 3', 'Name 4'],
);

sub GetEMailFor {
  my %names = ();
  foreach my $request ( @_ ) {
    if (ref ($Emails{$request}) eq 'ARRAY') {
      foreach my $em (@{$Emails{$request}}) {
        $names{$em}=1;
      }
    } else {
      $names{$request}=1;
    }
  }
  return join ',', map($Emails{$_}, keys %names);
}

print (GetEMailFor('Name 1', "Category2") ."\n");
[download]

Actually tested... and I leave the recursion that would allow categories to contain other category references as an exercise for the reader.

--
$you = new YOU;
honk() if $you->love(perl)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.