Why is the pronoun not used?

Question

I have my facebook in Spanish to practice my Spanish, but I was sent a message from facebook that didn't make sense to me in the way I understand some grammatical rules.

Anyway, here is the message I received. . .

"él envió un mensaje a los miembros del grupo"

Why isn't it: "él les envió un mensaje a los miembros del grupo"?

I thought when "a xxxx" (in this case "a los miembros") was used it required a pronoun. Or is it because "The members" are an impersonal object?

Thanks!

Answer 1

I think in this particular case, the direct object pronoun isn't necessary because you are using the "a xxx" language, making the direct object pronoun redundent.