It is a mail archive file, have a look here and can be open with Lotus.
Well I found a link, just check it out, might it’ll help: OL2000: (CW) How to Import Archived cc:Mail files into Outlook.
Updated link: Exchange Server Importer for Lotus cc:Mail Archives
- Download the app
- Browse to the folder of your language
- Run the app: ccmarch.exe
- Browse to and select the .CCA file(s) of interest
- Select the Outlook folder to which you want to import the selected file (I created a new ‘Personal’ folder: Personal_CCA