A bit more about Tarpit Interval in Exchange

I want to show the reasons why in the SMTP logs report of delays the delivery of emails.
Tarpitting is an artificial delay in server responses in SMTP for several reasons (preventing spam, directory harvest attack, high server load and etc.).
For convenience, I presented the information about log records, features (that responsible for the delay), delay values and etc. in the tables.

Feature	Recipient Lookup
Log	Tarpit for '0.00:00:05' 550 5.1.1 User unknown
Applicable	Exchange 2007 - 2016 on Edge Role
Delay default value	00:00:05
Delay minimum value	00:00:00
Delay maximum value	00:10:00
How to change delay value	Set-ReceiveConnector "Default" -TarpitInterval 00:**:**
Default feature state	Disabled. Need to enable Recipient Filter agent.
How to enable feature	Set-RecipientFilterConfig -Enabled $true
How to disable feature	Set-RecipientFilterConfig -Enabled $false Disable-TransportAgent "Recipient Filter Agent"
Comments	Authenticated connections are never delayed.
Technet	https://technet.microsoft.com/en-us/library/bb123891(v=exchg.160).aspx

Feature	Shadow Redundancy
Log	Tarpit for '0.00:00:05' due to 'DelayedAck'
Applicable	Exchange 2010 - 2016
Delay default value	00:00:30
Delay minimum value	00:00:00
Delay maximum value	00:10:00
How to change delay value	Set-ReceiveConnector "Default" -MaxAcknowledgementDelay 00:**:**
Default feature state	Enabled
How to enable feature	Set-TransportConfig -ShadowRedundancyEnabled $true Set-ReceiveConnector "Default" -MaxAcknowledgementDelay 00:00:30 (Exchange 2010)
How to disable feature	Set-TransportConfig -ShadowRedundancyEnabled $false Set-ReceiveConnector "Default" -MaxAcknowledgementDelay 0  (Exchange 2010)
Comments
Technet	https://technet.microsoft.com/en-us/library/dd351027(v=exchg.141).aspx

Feature	Back Pressure
Log	Tarpit for '0.00:00:55' due to 'Back Pressure'
Applicable	Exchange 2007 - Exchange 2016
Delay default value	00:00:10
Delay minimum value	00:00:00
Delay maximum value	00:00:55
How to change delay value	Modify SMTPBaseThrottlingDelayInterval, SMTPMaxThrottlingDelayInterval, SMTPStepThrottlingDelayInterval, SMTPStartThrottlingDelayInterval keys in "EdgeTransport.exe.config" file.
Default feature state	Enabled
How to enable feature	Open the "%ExchangeInstallPath%Bin\EdgeTransport.exe.config" file. Add or change the key "<add key=”EnableResourceMonitoring” value=”true” />" and save. Run "Restart-Service MSExchangeTransport" cmdlet.
How to disable feature	Open the "%ExchangeInstallPath%Bin\EdgeTransport.exe.config" file. Add or change the key "<add key=”EnableResourceMonitoring” value=”false” />" and save. Run "Restart-Service MSExchangeTransport" cmdlet.
Comments	Messages could delay due to Back Pressure only for "QueueLength[SubmissionQueue]" and "UsedVersionBuckets" resources with medium utilization level. For other resources due to Back Pressure all messages are rejected. Microsoft hasn't recommended modification back pressure settings in the EdgeTransport.exe.config file.
Technet	https://technet.microsoft.com/ru-ru/library/bb201658(v=exchg.160).aspx

Other tarpit logs that not yet explored by me:
Tarpit for '0.00:00:05' due to '535 5.7.3 Authentication unsuccessful'
Tarpit for '0.00:00:05' due to '554 5.6.0 Invalid message content'
Tarpit for '0.00:00:05' due to '504 5.7.4 Unrecognized authentication type'
Tarpit for '0.00:00:05' due to 'IP discredited'

P.S. Interestingly, Tarpit feature can be enabled in Microsoft Windows Server 2003.