I have a scenario.
In my organization we use Microsoft Exchange Distribution Lists of users. Now I have created a SharePoint site (2013), I would like to use these distribution lists to grant permissions to SharePoint site /folders.
SharePoint seems to be recognizing the groups but when added the error says
Sorry, you are not allowed to share this with external users. Although it is an internal mailer group.
These distribution lists are not AD distribution groups, although it acts like one, that I can simply change the same to Security Groups. Also note, I can't change the distribution list to a security group any how.
Please help me out here, is there any way I can start incorporating these exchange mailer list into SharePoint security model?