There are two different ways you may be able to share your FastMail calendar with other people. All users can get public calendar URLs that can be used to share a calendar (read-only) with other people both at FastMail and other calendar providers. Business and family accounts can also share calendars directly with other members of the business, and can grant write-access to the calendar.
Public calendar URLs can be used to share the information in one of your calendars with someone else, even if they use a different calendar system. There are two different URLs you can choose to share: one links to the full details of each event in the calendar; the other only reveals the times you are busy, but does not contain any information about the events themselves.
To enable the public URL for a calendar in your account:
The URLs are unguessable, but can be shared by whoever knows them to give another person access to the same information. If a URL gets shared with someone who shouldn't have it, you can use the Reset URL button to change to a new unguessable URL.
To add a public calendar URL that someone has shared with you to your account:
Business (and family) accounts can also share calendars directly with other users in the business. Sharing can be controlled more precisely than with public calendar URLs, and the other users can be given permission to edit the calendar, not just read it.
To share a calendar with someone else in your business:
Select the level of access you wish to grant. The options are:
Click the green Add button.
The calendar will now appear in the accounts of the people you shared it with. If you gave them write-access, they will be able to create new events, or modify and delete existing ones. Otherwise, all events in the calendar will be read-only.
You can revoke a user's access to a shared calendar at any time by going back to the same screen.