Exchange 2016 Event ID 1035 "Inbound authentication failed with error"

After installing CU4 on my Exchange 2016 servers and bouncing them, they started throwing MSExchangeTransportDelivery Event 1035 every few minutes.

Here's the full error:

Log Name:      Application
Source:        MSExchangeTransportDelivery
Date:          3/19/2017 10:30:14 AM
Event ID:      1035
Task Category: SmtpReceive
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      MBX1.exchangeitup.com
Description:
Inbound authentication failed with error UnexpectedExchangeAuthBlobCheckForClockSkew for Receive connector Default Mailbox Delivery MBX1. The authentication mechanism is ExchangeAuth. The source IP address of the client who tried to authenticate to Microsoft Exchange is [127.0.0.1].

The error, in this case tells you exactly what to look for. Check the system clocks across your Exchange servers and Domain Controller.

For now (to get Exchange running properly), manually set the clocks the same and then restart the Frontend Transport and Transport Services on each Exchange server.

Now, figure out why your clocks are wrong. If these are VM's, follow my post on how to set your VMWare host and guest clocks.
If they're hardware machines, prolly need to replace the CMOS battery, which prolly means if it's that old, you need to replace the server itself ;)