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Changed Exchange 2019 DNS MX Records for Spam Filter Service and Exchange Active Sync Now Fails

Michael Adams 311 Reputation points
2024-07-26T17:06:51.5866667+00:00

We have an on-premises Exchange Server 2019.  Everything was working fine until we got an external spam filtering service.  We changed our MX records to point to the spam filtering service, and then the filtering service sends the emails to the Exchange Server.  That part works great.

 

The problem is when we try to add an account to Outlook or a smartphone, it won't connect to the Exchange Server to setup the account.  The only records changed were the MX records.  Autodiscover, mail.{domain].com, and autodiscover records still point to the Exchange server.

 

Here are the error messages I get.

 

thumbnail image 1 of blog post titled Changed Exchange 2019 DNS MX Records for Spam Filter Service and Exchange Active Sync Now Fails

 

If I manually setup the Outlook profile putting in the mail server name (mail.{domain}.com, domain\username, password, etc., then I get this.

 

thumbnail image 2 of blog post titled Changed Exchange 2019 DNS MX Records for Spam Filter Service and Exchange Active Sync Now Fails

 

I ran the Microsoft Remote Connectivity Analyzer for Activesync, and it passed.

 

The autodiscover records look like this.

A autodiscover.mydomain.com XXX.XXX.XXX.XXX where XXX.XXX.XXX.XXX is the server public IP address.

A mail.mydomain.com XXX.XXX.XXX.XXX where XXX.XXX.XXX.XXX is the server public IP address.

SRV _autodiscover._tcp.mydomain.com 0 443 mail.mydomain.com

Some people use a CNAME instead of an A record for autodiscover.mydomain.com. I don't know if that makes a difference.

Anyone have any ideas or workarounds?

Exchange Server
Exchange Server
A family of Microsoft client/server messaging and collaboration software.
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Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Mike Hu-MSFT 2,655 Reputation points Microsoft Vendor
    2024-07-29T08:49:06.1033333+00:00

    Hi,

    Welcome to the Microsoft Q&A forum.

    When this message comes up, click Back, select Manually configure server settings then click Next.

    User's image

    You'll need to enter your account information and server names then click More Settings and configure your SSL or TLS settings on the Advanced tab.

    User's image

    Also, I recommend you update your SPF records to include the spam filtering service. If you're using DKIM, make sure the service is correctly signing outgoing emails.

  2. Andy David - MVP 1.5L Reputation points MVP
    2024-07-29T18:47:32.5533333+00:00

    the outlook client doesnt support ActiveSync.

    https://learn.microsoft.com/en-us/outlook/troubleshoot/profiles-and-accounts/outlook-cannot-use-activesync-connect-exchange

    Does it work if you use Outlook Mobile on a Mobile device?

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