For more information, refer to the Microsoft Office article Reduce the size of Outlook Data Files (.pst and. The only way to reduce the file size of a PST and reclaim white space is to compact the PST file.
If you add more data to the PST file again it will utilize this white space first, before expanding the file size again. If you don’t add any further data to the PST file, then this white space can contribute to a considerable storage cost as the PST file size on disk is considerably larger than the data it holds. If however you then remove data from the PST, the file size will not change only the data size is reduced.
However, PSTs created by Outlook will have a file size of 265KB on disk even though they don’t yet contain any data. As you add data to a PST file, it will expand the file size to accommodate the addition of data. Initially the PST file contains no data when first created. A user may also delete emails they no longer require from a PST file which reduces its data size.Ĭhanges in the data stored in a PST do not necessarily have a direct effect on the PST file’s size on disk. For instance, a user may move emails from their mailbox to a PST file which will increase the data size. PST files can have data added and removed from them under normal usage.
