It’s time for reminders in SharePoint

https://techcommunity.microsoft.com/t5/Microsoft-SharePoint-Blog/It-s-time-for-reminders-in-SharePoint/ba-p/299190

SharePoint lists and libraries have long allowed to you defined custom metadata columns to track dates.  As announced at Ignite 2018, we are releasing a new capability that lets you set reminders for any of these dates.  You’ll be able to receive a personal email alert ‘x’ days in advance of a date on any document or item in SharePoint.

https://techcommunity.microsoft.com/t5/Microsoft-SharePoint-Blog/It-s-time-for-reminders-in-SharePoint/ba-p/299190