There are currently problems with Exchange Server and the July updates for Windows Server. Microsoft has now withdrawn the faulty update and provided an updated version via Windows Update. The current update is KB4345418, Exchange Server should be updated as soon as possible to avoid problems with the MSExchangeTransport service.
Here is the corresponding article on the Exchange Team Blog:
Here are details about the new update:
KB4345418 also fixes a problem with a DHCP failover cluster where clients did not receive a valid IP configuration. SQL servers may also no longer start correctly with the old update. The latest update can also be downloaded directly from the Windows Update Catalog and installed manually:
In my case, however, it is already being distributed via Windows Update. Incidentally, the faulty update is KB4338814, so servers on which this update is installed should be provided with KB4345418 quickly.