An OLM file can be available on MS Outlook for Mac. The file extension is mostly used for MS Outlook to store a number of data including Contacts, Messages, Emails, Notes, Journals, Task, Calendar, and many more attachments. Any technical or non-technical user can use this software with ease. Use OLM to PST Converter for Mac and to learn how to change email file format from OLM to PST file format.