Google Calendar "Unknown senders" email invitations

Learn how to allow Google Calendar invitations from unknown senders to be added to your calendar automatically.

Google Calendar has added a new setting to help prevent spam. As of February 15th, this setting is enabled by default for some users. If you receive a calendar invitation from an email address that Google does not recognize, it will be marked as an "unknown sender," and the event will not be automatically added to your Google Calendar.

To change this setting and allow calendar invitations from unknown senders, follow these steps:

1. Click Settings on the top right-hand side of your Google Calendar.

2. Under the General tab, Select Event Settings.

3. Under Add invitations to my calendar, select From everyone.

You can also click on the "I know the sender" button when presented, which will add that email address to your Google Calendar safe senders list for future events to be added automatically.