One of the things you can now do with the version of Outlook via a browser (Outlook Web App) is actually take it offline in a browser. All the details can be found here:
However to enable all you basically need to do is open your Outlook Web Access
In top right of the window select the cog icon.
From the menu that appears select Offline Settings.
Then simply select Turn on offline access.
What else do I need to know (from article)?
Offline access may not make all of your email and calendar information available offline. Some of the available features and limitations are:
- The last few days of messages. Supported folders include Inbox, Drafts, and any folders viewed within the last few days, up to 20 folders. If you’ve viewed more than 20 folders in the last few days, the most recent 18 plus Inbox and Drafts will be available.
- In each folder that’s available offline, you will see three days of content, or 150 items, whichever is larger.
- Attachments aren’t available when offline.
- The previous month and future year of your calendar.
- A limited set of upcoming calendar reminders. If you’re offline for a long period of time, calendar reminders will stop working until you go online and Outlook Web App can download current information.
- Only your primary Calendar will be available offline.
- All the items in your Contacts folder, plus any people that you email often and any that you’ve emailed recently.
- Offline access doesn’t include archived folders, Team folders, tasks, or Favorites.
- You can’t search for or sort items in your mailbox when offline, and the built-in filters won’t work when you’re offline.
You have to enable offline access on each computer that you want to be able to use Outlook Web App on when not connected to a network.
Offline access for Outlook Web App is designed for portable computers such as laptops and notebooks. It can't be enabled in browsers on smaller devices, such as tablets and smartphones.
Your web browser determines where on your computer the offline information is stored and how much space it can use. If your offline information won’t fit in the space that’s been set aside, you may be prompted to increase it. If the space can’t be increased, less of your information will be available when you’re offline.