Many Exchange admins woke up today and seeing that Exchange is no longer processing emails. This is because Microsoft Filtering Management Service is stopping because it cannot handle the new date format.

The reason for this is because Microsoft is using a signed int32 for the date and with the new value of 2.201.010.001 is over the max value of the “long” int being 2.147.483.647.

This seems to be affecting Exchange versions 2016/2019

You can see this error within the Application Event Log where there is a bunch of errors stating “Cannot Convert 220101001 to long” or different Events stating 3811 and 5801 (with timeout of the MSExchange Antimalware Engine)

As of now there is no known fix from Microsoft, but there is a couple of workarounds to get mailflow up and running again.

UPDATE: Microsoft has added a fix in the link below, which requires some manual work. That does not require disabling the anti malware engine.

  • Run the Disable-AntiMalwareScanning.ps1 script from the Exchange install directory and restart the transport service
  • or Set-MalwarefilteringService -BypassFiltering $true -identity nameoftheserver

UPDATE: Microsoft has confirmed disabling the malware filtering is the only current workaround. While new signatures and engine updates have been released, they don’t seem to fix the issue. We’ll continue to wait for an official response from Microsoft. 

Here is also a post from Microsoft https://techcommunity.microsoft.com/t5/exchange-team-blog/email-stuck-in-transport-queues/ba-p/3049447


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