How to Convert OLM File to Outlook PST Simple Conversion Guide Start by installing a compatible OLM to PST converter on the computer. After launching the application, select the option for adding or opening an O L M file . Browse to the location where the O L M file is stored and select it for processing. The software may scan the selected file and display its mailbox folders in a tree-like structure. Depending on the O L M file, the structure can include In box, Sent Items, Drafts, Deleted Items, Contacts, Calendar, Tasks, and other folders. Reviewing this structure allows users to verify the source data before conversion.