Outgoing email encryption not working for SMTPserver

Md. Mahfuzur Rahman 346 Reputation points

We have two Exchange SMTP servers. when we sent mail by an SMTP server to Gmail, email encryption is not working.
we have installed the exchange SSL wildcard certificate on both SMTP servers then encryption mail is working for one server.
But another server is not working. I am sharing both screenshots below-


Not Working-


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. Aholic Liang-MSFT 13,826 Reputation points Microsoft Vendor

    Hi @Md. Mahfuzur Rahman
    In order to narrow down the issue, I wonder to confirm the following points with you:

    1. Are you sending mail using the Outlook client or OWA?
    2. When you send messages to your Outlook account, do you get a similar error?
    3. Is the certificate installed in the client that you sending the message?
      Here are two official Microsoft guides on how to send encrypted emails from outlook client or OWA, you can refer to for more information:
      Encrypt email messages - Microsoft Support
      Encrypt messages by using S/MIME in Outlook Web App - Microsoft Support

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