use strict;

my $file = "email_list.txt";
my %domains;

open(DATA,"<",$file) || die "Unable to open file '$file':  $!\n";

while (<DATA>) {
  my ($user,$domain) = split /\@/;
  $domain =~ s/^\s*//s;  # Stripping out leading white spaces
  $domain =~ s/\s*$//s;  # Stripping out trailing white spaces
  $domains{lc($domain)}++;
}

close(DATA);

foreach my $domain (sort keys %domains) {
  print "$domains{$domain} $domain\n";
}