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Cannot force TLS in Messaging Gateway for mail delivery to Office 365

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Article ID: 172192

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Updated On:

Products

Messaging Gateway

Issue/Introduction

  • Mail flow from the Symantec Messaging Gateway (SMG) to a Office 365 host has stopped
  • SMG has valid TLS certificates

454 Certificate Expired

Cause

TLS unable to complete the verification against Office 365 server because the Office 365 Certificate is expired/invalid/misconfigured.
 

Resolution

Workaround

  • Temporarily change the protocol operation for the domain in question: Protocols > Domains > "UserDomain" > Delivery > RLS Encryption Section
  • Change the radio button to "Require TLS encryption and don't verify certificate"

Solution

  • Solution is to contact Microsoft for resolution of the certificate issue in the Office 365 configuration.