Hope everyone is well. I am hoping someone here can assist me. Is there any way I can get a report in Office 365 that will tell me when last a distribution group was used? I have been tasked with removing all old distribution groups. Appreciate any advice.
There is no such report, you will have to go over the message trace events and find out when the last time a message was sent to a given group. Which might be a problem, considering the message trace events are kept for less than a month.
There's no way to extend the retention period. One of the things you learn soon about a cloud service is that the provider sets the rules and you have to obey. If you want to keep data for longer, you must copy it from Office 365 and store it somewhere like Splunk.