This is silly.
1) No one installed an edge server and used MS's built in protection. You do an edge server and use a 3rd party spam/antivirus
2) KB4013429 did blow up my edge server and this is the only post I've seen about it and this is over a week after KB4013429 was released. Come on man!
We are still running exchange 2016 edge on windows 2016. KB4013429 was installed before exchange and everything is working fine. EOP requires Enterprise CALs. Very few of my 600 users have Enterprise CALs and the cost would be stunning to add it.
This is clearly a bug and instead of trying to sell Office365 crap fix the problem.
[Rant](WE REALLY DO NOT WANT ANY OF IT! :) It cost more and this stuff isnt' hard to run in house. Also, we've had no major outages in years and MS cloud stuff have massive outages 2 times in the last few weeks!.) [/Rant]