use Email::Address;

my $addresses = 'aaa@z.com bbb@z.com ccc@z.com "John Doe" <doe@z.com> (John Doe) <j.d@z.com> ';
my @emails = Email::Address->parse($addresses);

for (@emails) {
    $_->address( $_->user . '@' . "something.com" ) if $_->host eq 'z.com';
}

my $new_addresses = join ' ', @emails;