Translation:Yo les mando cartas a mis amigos ingleses.
Because what you're really saying here is:
I send letters 'to them'.
to them = les.
les = a mis amigos ingleses (to my English friends) which is clarifying what les (to them) actually means.
But why say "to them" if that's not what Duolingo asked? Why not just "yo mando cartas a mis amigos ingleses"? Is that just how it's done in Spanish?
That’s exactly what I wondered too! Seems a bit of a long winded way to say it?
Unlike in English, in Spanish you always use the indirect object pronoun, even if you are explicitly stating the indirect object of the sentence. If you already include the indirect object explicitly (like "English friends" here) then the pronoun is just a placeholder but the grammar says it has to be there.
https://www.spanishdict.com/guide/indirect-object-pronouns On my own search I found this article, which provides a lot of helpful explanation and a quiz for practice. Unfortunately I still can't answer the heart of the question here, which is why "les" is required before the verb if you are going to say "a ellos" afterwards. I will ask my friends down here in Peru and report back.
Mando cartas a mis amigos ingleses = ( Yo les ) mando cartas a mis amigos ingleses
Except that Spanish still needs the "les" that we wouldn't use in English.
I disagree. If the sentence said I send them letters,( my english friends.) les is required. However,I send my friends letters, does not require les. DUO is wrong here
English does not require the indirect pronoun in this case. But Spanish does! Duo is correct!
The RAE agrees with milrecan---so Duo is wrong to require les. Reported.
The redundant pronoun is required only if the object itself is a pronoun---or if the object precedes the verb.
isnt it okay to say "yo les mando cartas a mis amigAs ingleses"??? it still means friends...
Yes, but it has to be amigAs inglesAs.
(amigo inglés, amiga inglesa, amigos ingleses, amigas inglesas)