Yes, SearchBlox supports indexing Outlook PST archives, including attachments contained within the emails using Email Collection.
SearchBlox does not require the Outlook Client or any other software to index the PST archives. Once indexed, the emails that are found during searches can be viewed through your browser.
The PST file is a personal folder file in Outlook created as a .pst file extension. Files are saved on your computer in the Documents>Outlook Files folder or My Documents>Outlook Files folder.
To learn more on email collections read: Email Collection in SearchBlox