When a meeting attendee replies to your meeting invitation, you receive an email with the reply attached. To update the meeting based on the reply, perform the following steps:
Open the email message to which the reply is attached.
Open the reply by viewing the attachment in the message, as described in To View an Attachment.
Click OK to close the reply.
Email and Calendar updates the attendee list, based on the details
of the reply.
Close the email message.