Is printout of the ticket mandatory?

It depends on the bus operator you are choosing to book the ticket. Some bus operator accepts the e-ticket whereas others do not. For those operators who support the e-ticket, you can produce the e-ticket received during the time of boarding itself. For the other operators who do not accept e-tickets, it is mandatory to carry a printout of the e-ticket sent to your e-mail ID at the time of boarding. We recommend our users to carry a printout of the ticket.