How to Uninstall Antispam Agents on Exchange Servers

UPDATE: The Exchange Team posted an article about this issue today. See Exchange Server Edge Support on Windows Server 2016 Update.

Microsoft announced that they were deprecating support for the SmartScreen spam content filter for Exchange Server in September 2016. See the article, Deprecating support for SmartScreen in Outlook and Exchange for full details.

All that is supposed to mean is that Microsoft is no longer producing anti-spam signatures for Exchange, but I discovered today that the Microsoft Exchange Transport service would not start on my Exchange 2016 Edge Transport servers after a servicing reboot. These Edge servers are running on Windows Server 2016. The Application event log shows the following error:

Log Name:      Application
Source:        MSExchangeTransport
Date:          3/17/2017 2:59:07 PM
Event ID:      16023
Task Category: Configuration
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      mail.contoso.com
Description:
Microsoft Exchange couldn't start transport agents. The Microsoft Exchange Transport service will be stopped. Exception details: Failed to create type 'Microsoft.Exchange.Transport.Agent.ContentFilter.ContentFilterAgentFactory' from assembly 'C:\Program Files\Microsoft\Exchange Server\V15\TransportRoles\agents\Hygiene\Microsoft.Exchange.Transport.Agent.Hygiene.dll' due to error 'Exception from HRESULT: 0xC0630005'...

The highlighted section in the error log indicates the problem is with the content filter, which is one of the antispam agents installed with the Install-AntispamAgents.ps1 PowerShell script. Whenever the MSExchangeTransport service is started, the service stops again within a minute and this event is logged.

The fix for me is to remove the content filter transport agent on the Exchange server(s) where the antispam agents are installed. Run the Get-TransportAgent cmdlet from the Exchange Management Shell to see if the antispam agents are installed. These transport agents include the Content Filter Agent, Sender Filter Agent, Sender ID Agent, and Protocol Analysis Agent.

To uninstall these agents use the Uninstall-TransportAgent cmdlet. For example,

Uninstall-TransportAgent -Identity "Content Filter Agent"
Uninstall-TransportAgent -Identity "Sender Id Agent"
Uninstall-TransportAgent -Identity "Content Filter Agent"
Uninstall-TransportAgent -Identity "Protocol Analysis Agent"

For me, all I really needed to uninstall as the Content Filter Agent to get the Transport Service to start.

Once you've uninstalled them you need to restart the Transport Service:

Restart-Service MSExchangeTransport

This will start the Microsoft Exchange Transport Service if it was already stopped and you're back in business. Of course, you still need a good antispam service for on-prem. I use Exchange Online Protection (EOP) which works very well for me and most of my customers.