WILL OUTLOOL 365 LEGACY CALENDAR on MAC still be able to work after the October 2026 cut off dsate?

Hello

That depends.

For Exchange online or outlook.com/hotmail.com calendar, the answer is no. That's because Exchange web services connection will be retired then, and Exchange mailbox relies on this to sync the entire mail box, including mails, calendar, etc, hence it will not work once the retirement happens.

If you have a local calendar on the computer, that's a different story as it won't require syncing via the EWS connection.