PIM
In the business world, outlook, both as an email and PIM tool has been Microsoft Office's killer app.
LibreOffice doesn't have that, and recommend using Mozilla Thunderbird.
https://wiki.documentfoundation.org/Feature_Comparison:_Mozilla_Thunderbird_-_Microsoft_Outlook
For a big chunk of business customers, Outlook IS office. Gmail has made inroads into breaking that chokehold, but I think Libre/Open Office could get a big boost with a full PIM Application.
Biting the hand that feeds IT
