It would be nice if it was considered as having been paid! It has to be paid and you can pay it either by literally forking out the money, or you can get authorisation for "virtual" payment.
Check out this webiste which explains exactly how you do that - there is a decreto legge that governs the alternative payment method

"Imposta di bollo sugli estratti conto inviati dalle banche ai clienti
Assolvimento in modo virtuale. di Roberto Tombolesi."

Angela