PST is a common file format of MS Outlook for windows.It is not supported by Apple mail and other email clients .If you are looking to access ms outlook database to Apple mail or other email clients ,conversion of .pst to .mbox will be helpful. this tool is easy to install and use  in your MAC.

Key features :
Export pst to mbox only
Convert filtered PST files 
Easy to configure & install
Advance level compatiblity 
Other advanced featues

It will not expire , you can use the app as long as  you wish. we will send you a notification to upgrade the app to improve its performance.

To know more : http://www.toolscrunch.com/mac-pst-to-mbox-converter.html