So they can say it's their service. Using somebody else's email service isn't their "serviceless". Of course there is a question of where you draw the line. But

So they can say it's their service. Using somebody else's email service isn't their "serviceless". Of course there is a question of where you draw the line. But IMHO, using somebody's email service is that line here. Otherwise it's not far from using gmail or aws WorkMail for that matter.