Exchange 2016 and SMTP speed

In order to have Exchange SMTP speed up a little you can change some default values.

Some of those values can be found here

So if you want to change some of those value, to accept more mail at the same time, and deliver faster (if your machine can handle it, because you believe it is sooooo fast) you could do:

( Warning: you deviate from Microsoft Standards here, plus
Warning: this way you set it for ALL Transport services )

Get-TransportService | Set-TransportService -MaxOutboundConnections 40

Get-TransportService | Set-TransportService -MaxConcurrentMailboxSubmissions 40

Get-TransportService | Set-TransportService -MaxConcurrentMailboxDeliveries 40

I find MaxOutboundConnections and MaxConnectionRatePerMinute to be fairly OK default settings for a small corporation, but you can go faster!

If you want to change those too, do, e.g. twice as much:

Get-TransportService | Set-TransportService -MaxOutboundConnections 2000

Get-TransportService | Set-TransportService -MaxConnectionRatePerMinute 2400

And there’s tarpitting ofcourse, that adds an extra delay. (mind you, tarpitting has its reasons)

If you want to lookup the current values on your server, do

Get-ReceiveConnector | Select Name, Tarpitinterval

If you want to turn that off do:

Get-ReceiveConnector | Set-ReceiveConnector -TarpitInterval 0

Be sure to restart the transport service.

Always do a get command, just in case you have not noticed its values.

Of course you can do calculations on how much bandwidth your server has, can handle, and can spew out, and how many IOPS are needed for average mail transactions to your Exchange database, etc, but this post is not about that. I usually list how to do stuff. Not how to do stuff proper 🙂 Also, never say, has it so it must be true. I don’t have the time discussing if something is true. What I hope that is that most of the time it works.

Hope this helps you!

P.S. For Exchange 2010 you can do things like the following, but look them up first, so that you know what you did, before you screwed up your exchange machine.

Get-ReceiveConnector | Set-ReceiveConnector -MessageRateLimit 4000
Get-ReceiveConnector | Set-ReceiveConnector -MessageRateSource None
Get-ReceiveConnector | Set-ReceiveConnector -MaxInboundConnectionPercentagePerSource 30
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