Exchange Server 2016 Hybrid EXO Throttling

Steve_1337 0

Hey folks,

maybe somebody here have a hint for me. The MS Support is not very helpful.

Our mails connecting to EXO are blocked for 60 mins/hr, so forever. Actually I have paused throttling / blocking for 2 weeks now. In this time the MS support was not able to help me.

The actual build number for our Exchange DAG is 15.1.2507.39, so the newest available build. BUT 1 Server in the DAG hast the build number 15.1.2507.17 in his header. And I assume this is the reason for the throttling.

btw, online in the out-of-date connecting on-premises Exchange servers report, the status is "resolved". But you can see that the mails were blocked. -> this must be a bug.

User's image

The only way MS can read the build number are the headers and because of that I think it has to do with the false SMTP server ID from this one Server.

2 answers

Xintao Qiao-MSFT 3,695 Reputation points Microsoft Vendor

2024-09-25T02:31:45.1333333+00:00

Hi, @Steve_1337

It sounds like your EXO connection and local Exchange server are experiencing mail throttling.

1.Make sure that all servers in the DAG are running the same version. The server with build number 15.1.2507.17 should be updated to match the other server (15.1.2507.39).

Exchange Server build numbers and release dates | Microsoft Learn

2.If a difference in build number is causing the problem, you need to update the outdated server.

Upgrade Exchange to the latest Cumulative Update | Microsoft Learn

3.Check the full SMTP headers of the blocked email to see exactly what server information is being used and diagnose if an outdated server is indeed the problem.

4.You can read these two articles on how to pause throttling and block obsolete on-premises Exchange Servers.

Throttling and Blocking Email from Persistently Vulnerable Exchange Servers to Exchange Online - Microsoft Community Hub

How to pause throttling and blocking of out-of-date on-premises Exchange Servers - Microsoft Community Hub

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Steve_1337 0 Reputation points

2024-09-26T10:35:01.71+00:00

Hey @Xintao Qiao-MSFT , thank you for your answer, but it is not helpful, because all my servers are up to date. As described the header information itself is outdated on one of them. The installed Version and Build Number are all the same:

[PS] C:\Windows\system32>Get-ExchangeServer | ft Name,Edition,AdminDisplayVersion

Name Edition AdminDisplayVersion

Enterprise Version 15.1 (Build 2507.17) Enterprise Version 15.1 (Build 2507.17) Enterprise Version 15.1 (Build 2507.17) Coexistence Version 15.1 (Build 2507.17)

[PS] C:\Windows\system32>$ExchangeServers = Get-ExchangeServer | Sort-Object Name

[PS] C:\Windows\system32>ForEach ($Server in $ExchangeServers) {

Invoke-Command -ComputerName $Server.Name -ScriptBlock { Get-Command Exsetup.exe | ForEach-Object { $_.FileversionInfo } }

}

ProductVersion FileVersion FileName PSComputerName

15.01.2507.039 15.01.2507.039 D:\Program Files\Microsoft\Exchange Server\V15\bin\ExSetup.exe

15.01.2507.039 15.01.2507.039 D:\Program Files\Microsoft\Exchange Server\V15\bin\ExSetup.exe

15.01.2507.039 15.01.2507.039 D:\Program Files\Microsoft\Exchange Server\V15\bin\ExSetup.exe

15.01.2507.039 15.01.2507.039 D:\Program Files\Microsoft\Exchange Server\V15\bin\ExSetup.exe

Xintao Qiao-MSFT 3,695 Reputation points Microsoft Vendor

2024-09-27T07:25:21.2533333+00:00

Hi, @Steve_1337

1.When a custom message ID is overwritten by the SMTP server's message ID, the SMTP server may change the message ID, which causes mail threading and recognition issues. Verify that the SMTP server information is correctly configured, such as the server name and port.

2.Are you running unsupported software on your server, which also causes Microsoft to increase the limit and block the mail.

3.If possible, migrate servers to the cloud as early as possible to avoid certain issues.

4.Based on the information I found, older versions of Exchange, such as Exchange 2016 CU8, may have some known issues that have been fixed in subsequent updates. It's important to make sure your Exchange servers are running the latest cumulative updates (CUs) to avoid such issues.

More information can be found Microsoft's Plan to Block Old Exchange Servers | Practical365

5.You can also open a support ticket with Microsoft for a more in-depth investigation.

Global Customer Service phone numbers - Microsoft Support

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Xintao Qiao-MSFT 3,695 Reputation points Microsoft Vendor

2024-10-02T09:24:26.0066667+00:00

Hi, @Steve_1337

Just circling back to check to see how things are going on with this thread. Should you need more help on this, you can feel free to post back.
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Steve_1337 0 Reputation points

2024-10-07T06:58:50.1666667+00:00
Hey @Xintao Qiao-MSFT ,

where could I find this? I don't think so but I don't know how to find this.

Nope

we don't want to AND it has to work

I know, I found this too, but ALL my Servers are up to date and the newest CU ist installed.

Already happened and also not very helpful
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Xintao Qiao-MSFT 3,695 Reputation points Microsoft Vendor

2024-10-08T07:52:53.2166667+00:00

Hi, @Steve_1337

Ensure that the SMTP server name and port are specified correctly. For example, the server name might be smtp.office365.com and the port might be 587. Server settings you'll need from your email provider - Microsoft Support

If you are setting up an on-premises SMTP server, make sure it is installed and configured correctly. For example, on Windows Server, you may need to add the SMTP server feature and configure it through the IIS Management Console.

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Exchange Server 2016 Hybrid EXO Throttling

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