Understanding what “This Computer Only” folders mean
Something that many people are not aware of/don’t pay attention to is the change in the type of data file used to store IMAP data in Outlook ‘2013/’2016 which is now an .ost file versus a .pst file used in earlier versions of Outlook.
To review the difference between earlier and current and Outlook versions is that in OL’2010 and earlier, IMAP email folders were contained in its own PST file and contact/calendar data was stored in a separate PST file or to be more specific, contact/calendar folders were stored in the default data file for the Outlook profile.
Starting with OL’2013, all data is stored in a single .ost file including contact/calendar folders which have the added description of “This Computer Only”. The IMAP protocol does not sync contact/calendar info with the server and in essence, any contact/calendar information remains local to the computer on which the account has been configured – hence the words “This Computer Only” for those folder types.
The change to a single OST file also has some other significant ramifications which may lead to a complete loss of contact/calendar data. This would occur if the email account is deleted which results in the underlying OST file is also deleted. Even if you made a copy of the OST file and then re-added the same email account to Outlook, a new OST file will be created, the email folders will be sync’d with the server and the contact/calendar folders would be empty. There is no capability to re-use an existing OST file which can only be opened by the original Outlook profile/email account used to create it.
There is a simple way to protect against losing contact/calendar data by creating a PST file and setting it as the default for the profile – see How to Protect Outlook ‘2013/’2016 Imap Contact/Calendar Data
The underlying premise for this article is that a single IMAP email account is involved. Things can be different depending on the number and types of additional email accounts are involved and whether or not the IMAP email account was the first configured in a multi-account environment.
Category: Understanding Outlook
