LawToolBox is an online, rule-based deadline calculator that I reviewed in some depth in 2013. Ever since 2013, it has integrated with Microsoft Outlook through an Office 365 app. But the integration was one way, meaning that all calculations and changes had to be made through the LawToolBox website, after which they would be automatically added to an Outlook calendar.
Now, LawToolBox is preparing to launch a new, more robust integration called LawToolBox365, which will be an add-in for Outlook 2013 and 2016 that will reside entirely within Office 365. It will be available for purchase in late May.