Microsoft has launched modern dynamic distribution lists, a mechanism to make the calculation of list membership more reliable and robust.| Office 365 for IT Pros
It's time to check recipient filters for dynamic distribution groups to ensure that you don't have any wildcard prefixes used with the -eq operator to find recipients based on their email addresses. A November 30 update will stop this kind of recipient filter working, and might have a knock-on effect on other processes.| Practical 365