\D+ stands for "non-digit repeated". You want "alphanumeric repeated", so try 
while ( /([[:alnum:]]+)(\@dh\.nl)/g ) {
    my ($name, $domain) = ($1, $2);
    print "$name$domain\n";
}

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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: using regular expressions showing just the hits. by choroba
in thread using regular expressions showing just the hits. by fritsimeel

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