Grammar rules say that when converting a sentence from direct speech to indirect, the reported speech is converted to past tense if the first part of the sentence (reporting verb) is in the past tense.
Direct speech: John said, “I will give you a pen”.
Indirect Speech: John said that he would give me a pen.
S1: I wanted to let you know that he has sent you an email
S2: I wanted to let you know that he had sent you an email
I have seen people write S1 even though it doesn't follow the grammar rule regarding change of tense in the reported speech.
Which of these ones correct and incorrect? Why correct and why wrong?