$data = 'any number of td/tds><td>stuff</td><td>email@email.com</td><td>more stfff</td><td>next@next.co.uk</td><td>r.h@a.com</td>';

my %addresses;
@emails = ($data =~ /<td>(.*?\@.*?)<\/td>/g);
    for (@emails) {
        $_ =~ s/.*<td>(.*)?/$1/g;
        $addresses{$_} = 1;
    }
}
for (keys %addresses) {
    print "$_\n";
}