Webmail, contacts, calendar, and other task services are just a few of the features available in Outlook. So, you must know how to set Outlook as the default mail client on Mac, Windows 10, Chrome, and Adobe. You should go to your Outlook account. Then, click on the 'file' and head over to the 'options.' Under the 'Options,' you will get 'General.' You need to check the 'Make Outlook the default program for Email, Contacts, and Calendar' option under the 'Startup option.' Now, check to mark the box of Outlook, and it will set Microsoft Outlook as a default mail client.