I am surprised that nobody reported this yet…
I upgraded from 7.8.6 to 7.8.7 on my test instance (copy of production)
I discovered that the email creation form is problematic
ALL the labels are undefined…
see
Before posting I downloaded a fresh FULL 7.87 instance and installed as new installation…
and the picture above came from the full & new 7.87
[strike]
I will report also on github…[/strike] update : before posting on github I saw it reported (did not see it before (?))
test instances running windows 10 and windows server 2016
IIs and Mssql 2012 php 7.0 /5.6 have similar problems