#!/usr/bin/perl
use strict;
use warnings;

my %email_domains;
for my $email_address (@email_list) {
  my ($before_at, $after_at) = split('@',$email_address);
  push @{$email_domains{$after_at}}, $before_at;
}

for my $domain (sort keys %email_domains) {
  my $count = @{$email_domains{$domain}};
  print "$domain: $count";
}