When I try to email a photo, and want to go to Email Account Manager to change or update my email accounts, Lightroom immediately crashes.
I am able to send mail using Microsoft Outlook with no issue, I just can't make any changes or updates to what is configured.
Lightroom CC 2015.12
Windows 10 v1703
Works here on 2015.12 and OS X 10.11.6
Have you checked the crash log error? Please share the crash log error with us.