Dear colleagues,

Microsoft 365 will deprecate legacy TLS cipher suites lacking forward secrecy on October 20, 2025, supporting only specified TLS 1.3 and 1.2 cipher suites. Most modern devices will keep working. Old devices or apps that use outdated encryption may not be able to connect after October 20, 2025.

Recommendation:

• • Use a modern browser: Microsoft Edge, Google Chrome, Firefox, or Safari. Do not use Internet Explorer.
  • Keep your Microsoft 365 apps (Outlook, Word, Teams) up to date.
  • If a copier/scanner sends email, make sure it uses current security settings or contact your local IT support.

Potential impact:

Older devices or apps might show errors like “cannot connect securely” or “TLS/SSL error” and fail to connect to Microsoft 365 services.

Learn more:

• • Microsoft full announcement 
  • Server cipher suites and TLS requirements
  • Manage TLS and cipher suites in Windows Server
  • Exchange Online – set up and validate connectors
  • Exchange TLS configuration best practices

Kind regards,  

Enterprise Applications & Solutions Integration (EASI) 

Information Technology Services  

University of Toronto