Originally adapted from The Technology Press. Substantially reviewed and updated 15 September 2026.
Still opening email does not mean still supported
An Outlook installation may continue to connect after its product support ends. Connectivity is not the same as receiving security fixes or being in a supported configuration. Record the actual product edition and version before deciding what to do.
This guide replaces the old 2021 connection-block list. Microsoft’s lifecycle and configuration guidance is the better reference for today’s upgrade plan.
Office 2016 and Office 2019 support ended.
Microsoft lifecycleOffice LTSC 2021 reaches end of support.
Microsoft lifecycleMicrosoft 365 Apps needs an appropriate update process.
Check your configurationPractical checkpoints, not a guarantee of security or compliance.
What to check
Identify what is installed
Record the product, build, operating system and update channel.
What to check
Distinguish classic Outlook, new Outlook and perpetual Office editions. Their features and support arrangements are not interchangeable.
Test the dependencies
Check the tasks your business relies on.
What to check
Include add-ins, shared mailboxes, document workflows and specialist integrations. Pilot the proposed version before a broad rollout.
Plan the supported path
Assign an owner and a realistic upgrade date.
What to check
Confirm licensing and deployment options, communicate the changes and verify updates afterwards. A working connection should not be treated as a security exception without an explicit plan.
Sources & further reading
Make the next step practical
Talk to ITFR about your business, priorities and the controls that fit.
