Simple one here – a VIP relies on a Gmail account when the company is on Office365. To allow the VIP to send to a distribution list, I had to do the following:

1) Open Exchange Admin Center
2) Click on Recipients and then Groups
3) Select the distribution group
4) Click the edit button edit icon

distribution-groups-list

5) Click Delivery Management and select “Senders inside and outside of my organization

delivery-management

6) Then just click Save! save button

You can also use this area to block or allow certain senders to distribution lists by adding emails to the box below.