Can you help me versus Can you do something for me

[Tedwonny]

I read in a grammar book that the first sentence below is wrong because by using 'help', you do it together. The second sentence is correct.

1) Can you help me post this letter, please? 2) Can you post this letter for me, please?

I was thinking if this is really the case. Yes, both do sound correct but I really doubt if native speakers don't say the first one in casual conversational English. The first, by common sense, doesn't mean both the speaker and the listener taking the letter to the post office, does it?
When we use 'help', does it really have to involve both parties, namely the listener(s) and the speaker(s)?

Thanks

 

[emsr2d2]

You could say "Can you help me by posting this letter?" That means the same as "Can you post this letter for me?" but it adds in the information that doing so would be helpful for you.