Charged already?

Hello am new to all this here BUT after having setting up this mail service (AWS workmail) we are being charged and am not YET using it to send/receive anything for the client?? Have just verified it's working . . . . Was under the impression this was charged by usage BUT seems being charged for having setup service and verifying emails(2 email accounts setup)?? Not sure I am explaining this clearly BUT am being charged even though NOT sending emails or newsletters (it's planned use)?? What can I expect costs to be because with just minimal usage of emails, So far have ONLY used to verifying emails so what will in fact be those costs when ACTIVE? Expected to be ONLY sending hundreds of emails and newsletters?? Thank you in advance for ANY help/suggestions!

Amelia