Dear Customers,
On the morning of November 1st, we identified delays in outbound mail queues within Office 365 tenancies. Our investigation revealed that, as of 8:00 PM GMT on October 31st, Microsoft Office 365 had stopped delivering emails to archives for numerous tenants globally.
Our analysis pinpointed that the issue stemmed from TLS 1.3 session negotiation failures between Office 365 and Cryoserver Online. To quickly restore functionality, we implemented changes to disable TLS 1.3, ensuring all communication proceeded over TLS 1.2. By 2:00 AM on Saturday, November 2nd, these adjustments were successfully deployed across all production archives. We were pleased to observe the backlog of inbound emails processing smoothly, confirming the resolution of the issue.
We apologize for any inconvenience this may have caused and appreciate your understanding as we worked swiftly to resolve the situation. It’s important to note that Microsoft deprecated TLS 1.1 on October 31st, with full support for TLS 1.0 and TLS 1.1 on Azure ending by October 31, 2024. This should not have affected Cryoserver Online operations, as we phased out TLS 1.1 several months ago. Moreover, TLS 1.3 encryption has been fully supported within Cryoserver Online for an extended period.
Our team will continue to monitor the use of TLS 1.3 with Office 365 closely and will re-enable this protocol only once we are confident of its stability. We also want to reassure you that we believe all emails sent to archives have been processed without loss. If you have received Non-Delivery Reports (NDRs), please raise a support ticket to facilitate the import of these emails.
Thank you for your patience and trust as we work diligently to provide you with a secure and reliable archiving solution