Rule reminder
CAUSE (indicative): 'Ho chiamato perché ero preoccupato' — the worry is the reason I called (past happened). PURPOSE (subjunctive): 'Ho chiamato perché tu SAPESSI la verità' — I called so that you would know. Key: CAUSE = the reason something happened (backward-looking). PURPOSE = the intended outcome (forward-looking, volitional). Sequence of tenses applies to both.
Gli ho mandato un messaggio perché _____ della riunione. (sapere)