Quick note of interest:

Be aware that when an Office365 distribution group is created, it will by default deny email from users outside the Exchange Online organization. I tried to send an email to our info address:

O365 Distro Group senders

Exchange 2013 distribution groups are not sender-restricted by default, so this took me by surprise. I’m glad I tested delivery before, for instance, publishing the address on a traffic-driving website.

To solve the issue, navigate to your Office365 Exchange Administration Center and either

  • enable senders inside and outside your organization, or
  • restrict allowed senders to a specific list of addresses (external and internal).

O365 Distro Group senders 2

All Done:

O365 Distro Group senders 3