How to solve “Unable to expand any Distribution List on Outlook/OWA”?

Sometimes the recipient group list or the “Distribution List” (DL) will not expand and will not show members of that distribution list on a new email inside ‘TO’ address bar. In this post, let us understand how to solve this problem.

Symptom

When this problem occurs, end users can send (but not delivered) email to those distribution lists which will move and exists inside “Sent Items”. But those emails will not be delivered to the member of those distribution list.
All the distribution lists which are lying on AD domain server can be impacted by this problem.

Cause of this problem

The permission level on the Active Directory has been changed from Universal to Global.

How to resolve?

• Go to properties of any one of the distribution list and on the General Tab make sure that Group Scope level is ‘Universal’. 
• After changing group level end users can review the members of those distribution lists by expanding it on Outlook inside ‘TO’ address bar.

This issue arises on Active Directory server, therefore no need to investigate MS Exchange Server.