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Douwa29's avatar
Douwa29
Copper Contributor
Jul 23, 2024

Exchange On Premise - MTA-STS protocol

Hi,

 

I read Enhancing mail flow with MTA-STS | Microsoft Learn and only Exchange Online is discussed.

 

Exchange On Premise doesn't seem to be mentioned.

 

So I have two questions:

 

- Can I consider that MTA-STS protocol is also supported by Exchange On Premise since it is supported by Exchange Online?

- If necessary, what Powershell command should I do to confirm this?

 

Thank you in advance for your answers.

 

François.

Exchange Server

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  • Andres-Bohren's avatar
    Andres-Bohren
    Steel Contributor
    May 17, 2025

    Hi Douwa29​ 
    You can use MTA-STS for Inbound Traffic. As long as the Sender Supports MTA-STS that will work with any SMTP Server.
    Exchange Server does not use MTA-STS when sending Outbound Traffic.
    Kind Regards
    Andres

  • HarperParker's avatar
    HarperParker
    Iron Contributor
    Apr 05, 2025

    1. DNS settings 
    Add this TXT record: 
    _mta-sts.your-domain.com → "v=STSv1; id=20240301" 
    2. Create an A record: 
    mta-sts.your-domain.com → your mail server's IP 
    3. Create a policy file 
    on the website https://mta-sts..com/. well-known/mta-sts.txt Place the content: 
    text 
    version: STSv1 
    mode: testing 
    mx: your mail server 1. your domain.com 
    mx: your mail server 2. your domain.com 
    4. Run this command (Exchange Management Shell): powershell 
    Set-TransportConfig -TLSSendDomainSecureList "your domain.com" 
    5. Authentication tools: 
    Visit https://mta-sts.internet.nl Enter your domain name to test 
    6. Modify the policy file: 
    text 
    version. STSv1 
    mode: enforce # Change to enforce mode 
    mx: your mail server 1.yourdomain.com 
    max_age: 604800

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