We are in the process of migrating all of our users to 365 and last week complete moving all 12K+ users to the could which included recreating all DL in Office 365. After getting a large number of calls about users not being able to receive emails from outside sources and other delivery problems, manage request we recreate all DL onprem again and remove them from the cloud as to stabilize the environment until a better action place on move forward was found. What is the best and safest way to slowing move all onprem DL's to Office 365? I have ready of that you can create a DL or contact onprem and point this to the out DL in someway. What are all of our options?