To customize the email invitations that go out to your meeting invitees, navigate to the Send Invitations tab under Advanced Options when creating or editing a meeting. You'll see a check box that says, "Send a customized invitation email." Click on it to see the feature highlighted below:
Custom Invitations enables a text field with a built-in text editor, where you can edit the text of the default email template sent out to your meeting guests.
In this text field, you can make use of placeholders such as {start} and {finish} which are variables for the start and finish time of your event, respectively. Various available placeholders are also shown under the field.
You can also enable first and second reminder emails, decide when they will be sent, and even customize each.
You can also attach files to the invitation, set reminder emails, and get copies of these emails sent to yourself.