Sending reminders is a feature of Premium Doodle. Sending a helpful reminder is the best way to organize your meetings fast. To be able to send reminders you have to send out your invitations via Doodle, rather than sharing the participation link. Click the 'invite' button at the top of the page and then 'email.' If you connect your address book, emails will autofill as you type. This is also the way you can track who is missing from you invitations. You'll see their email addresses listed as placeholders at the bottom of the table.