How can I open Outlook PST files read-only in Outlook 2010

Question

Running Outlook 2010 on Windows 7

I have two quite large outlook files each about 700MB each. I need regularly to access the emails in them, they are archives from recent years. However each time I open them, the date (and maybe something internally in the file) gets updated, this means that my backup software tries to back them up again during an incremental backup. I would like to open the PST files read-only (and of course for indexing searching too) so that the dates and the files are not changed. I don't really want to exclude them from backups, as I would like them in the full backup.

If I set the file to be read-only on the filesystem then outlook refuses to open it.

So to summarize the question again. How can I force outlook 2010 to open some PST files read only so they are available for reading, indexing and searching, but don't get changed.

Answer 1

I'm assuming Outlook 2010 has similar architecture to Outlook 2007. My source is specific to Outlook 2007 and lower, but I doubt anything has changed.

You cannot, by design. Indexing, reading, and searching write to the PST file.

Source: http://support.microsoft.com/kb/269520

From the article:

There are three reasons why Outlook does not support opening personal folders (.pst) files on read-only media (such as, CD-ROMs) or read-only folders:

The .pst file is a database file format. As the user navigates through the Outlook user interface, the user expects the computer to respond with searches and sorts (similar to when a user clicks a view column header to sort the content in the view). The computer must be able to write to the .pst file so that those search and sort procedures are available.

The user expects to be able to change the view contents, for instance the user may want to add columns, and the user may want Outlook to remember the current sort order, filters, and so on. The view definition saves the information into a special area in that Outlook folder, therefore the view definition is written to the .pst file.

The .pst file is in a single-user file format. The computer uses a special area of the file to write information about the computer that opened the file. The file allows other processes on the same computer to access the file while it prevents other computers from accessing the file until the first computer closes the file. Without this "file lock" feature, the computer is open to file damage when two computers open the .pst file at the same time.

These design decisions reflect the core architecture of Outlook and Messaging Application Programming Interface (MAPI).