Google Calendar Invitations - "Unknown Sender" emails.

Google Calendar's new policy to combat spam affects all scheduling tools, including Calendly. Calendar events are automatically added only if you've interacted with the invitee before. First-time invitees will need to confirm their booking by clicking a link in their email.

How to change this setting in a Google account

• 1. Click Settings on the top right hand side of your Google calendar.
  2. Under General, select Event Settings.
  3. Under Add invitations to my calendar, select From everyone.
     
     
     
     
• You can click on the "I know the sender" button when presented 
• Once you have done this, you will need to click Yes on the event invitation to ensure it is added to your Google calendar.

Additional recommendations

Below are a few other recommendations to keep your meetings visible to your invitees:

1. For Standard, Teams & Enterprise users, we recommend setting up email reminders and SMS messages within workflows. This can help you get ahead of low attendance or no-shows for your scheduled meetings.
   
   
2. For other users, you can link the Google support steps to your booking page confirmation page. Using a custom link labeled "For Google Calendar Users", your invitees can easily be redirected to the steps to change their default settings. 
   
   
   1. From your Event types page, open the event type you wish to edit. 
   2. Select More options at the bottom of the editor. 
   3. Expand the Confirmation page section.
   4. Select + Add new link.
   5. Enter the link and link name.
   6. Select Save changes.