Smtp ( not working in my shop channel

I have configured my email system to use SMTP ( for sending emails with correct details. However, I am facing an issue specifically within my shop channel where emails are not being sent successfully. Despite correctly configuring SMTP, emails initiated from the shop channel fail to be delivered or are not processed as expected. This problem is significantly impacting the functionality of email communications related to my shop operations.
here is the mail error response :
„status“: „400“,


        "title": "Bad Request",

        "detail": "Failed sending mail to following recipients: {{ recipients }} with Error: Unable to connect with STARTTLS: stream_socket_enable_crypto(): Peer certificate CN=`\u0027 did not match expected CN=`\u0027",

how to fix it