
By mixing locally stored data ("This computer only" folders) and cache data in a single ost-file, you cannot afford to lose the ost-file anymore either as it is no longer "just a cache".Another benefit of this was there was no need to back up your IMAP cache when switching computers just reconfigure the account and you are good to go again once the cache had been created.The beauty of this is that whenever something happens to your cache, you'd simply delete the ost-file of the IMAP account (which was a pst-file in Outlook 2010 and previous) and Outlook would re-cache a fresh copy again.This means that there will always exist a "master copy" of your data on the IMAP server and changes are also being replicated to the server.

IMAP mail folders are being cached on the local computer in ost-files.However, from a technical and backup perspective, this isn't a change which should be taken lightly at all. Especially when you use Outlook with a single (IMAP) account, this configuration is a welcome change as all your Outlook data is contained in a single folder list.

The new method in Outlook 2013 and later, to contain non-mail folders within the IMAP ost-file, of course has its benefits as well. Outlook 2013, 2016, 2019, and Office 365 default: Leave things combined For detailed instructions see: Hide, move or delete an Outlook folder via MFCMAPI. Note: If you don’t want to re-cache your entire mailbox, you can use MFCMAPI as well to get rid of the additional “This computer only” Calendar, Contacts, Tasks, etc… folders. Set a pst-file as the default data file to make sure you don't lose any non-synched folders (click on the image to see the view dialog).

/001-set-up-yahoo-calendar-ical-sync-1170760-3d748fe39c3c48679e8a9c315e173fcd.jpg)
In Outlook 2010, Calendar and Contact items were stored in a separate pst-file from the mail items but in Outlook 2013, 2016, 2019, and Office 365 everything is included in the single IMAP ost-file.Īctually, I should say "everything can be included", as it is only required to do so when you set your IMAP data file as the default in Outlook 2013 or later. This includes my Calendar and Contacts folder as well which I really cannot afford to lose. These folders I indeed cannot find back on the server. I'm using an IMAP account in Outlook as part of Office 365 and I noticed that various folders now have "This computer only" behind them.
