Major Incident Review - Unable to Apply Signature on Email for On Premise Users

Major Incident Review - Unable to Apply Signature on Email for On Premise Users

Major Incident Causing Product - Code Two of Exchange
Affected Users - On Premise Email Users 
Date - March 10, 2019
Tests Performed
      Scenario 1 - Updated the new image on Mailbox Server on each site - Signature was not applied for all on prem users
      Scenario 2 - Restarted the code two services - Signature was not applied for all on prem users
      Scenario 3 - Updated the new image on All Mailbox Server on each site - Image was not applied for all on prem users - Signature was                                   missing for all on prem users
      Scenario 4 - Restarted the code two services - Image was not applied for all on prem users - Signature was missing for all on prem users

Why it Happened - The Signature rule was not being picked up. and this is under investigation
How it was Solved - Created a new rule and applied it.
How to Avoid Recurrence - We upgraded it from Version 9 (which was not a supported version) to Version 12 (latest version).

Beza Melaku