update: of course, as runrig points out, this all depends what you have planned for this data. there is more than one way to do it.

That looks like a hash of lists, as in:

my %files = ( 'him@here.com' =>[ 'test1.txt', 'test2.txt', 'test3.txt'
+],
              'her@there.com' => [ 'test3.txt' ],
              'it@where.com' => [ 'test2.txt', 'test1.txt' ] );

or generically:

my %files2;
foreach( <LINE> )
{
  chomp;
  my ($email, @list ) = split( ',', $_ ); #assumes no commas in data f
+ile!
  $files2( $email ) = \@list;
}

and access looks like:

my @list_of_files = @{ $files2{ $email } };
[download]