Rule reminder
Summary: (1) Modal verbs: double pronoun can go BEFORE modal OR attach to infinitive. (2) Affirmative imperative (tu/voi): pronoun ALWAYS attaches. (3) Formal imperative (Lei): pronoun goes BEFORE. (4) Negative tu imperative: pronoun before infinitive or attached — both correct.
Context: modal verb (dovere). 'I must send it to you (sg.)' (la mail). Which is correct?