Office 365: Outlook Requirements

This article relates to Outlook software versions that are no longer supported on the Office 365 system.

There are three sections to this article:

Determining That There Is An Issue
The Basic Authentication Issue
Installing The Newer Office 365 Suite

Determining That There Is An Issue

If you are receiving the following error:

Your Microsoft Exchange administrator has blocked the version of Outlook that you are using. Contact your administrator for assistance.

Or this error:

This feature has been disabled by your administrator.

The images showing the error:

The likelihood is the version of Outlook you are using is not supported.

As of writing at November 2022, the following versions of Outlook (or older) are not supported by Microsoft via Office 365 services:

Outlook 2013
Outlook 2010
Outlook 2007
Outlook 2003
Outlook 2002
Outlook for Mac 2011
Outlook for Mac 2001

As this is the case you would either:

Continue using Outlook via Outlook for the Web - https://outlook.office.com
Install a newer Office 365 software - see "Installing Newer Office 365 Suite" below.

Please see the following article for more information:

Office versions and connectivity to Microsoft 365 services

The Basic Authentication Issue

Microsoft are forcing "Modern Authentication" connections.

Early January 2023 it will no longer be possible to use "Basic Authentication" to connect to Office 365 Exchange online; note that Microsoft have disabled this sooner for some Tenants.

The issue presents as the following while in Outlook:

As this is the case, if you are experiencing this issue you will need to upgrade the Office 365 suite to be able to connect with the local Outlook software to the Office 365 Exchange online service.

If it is not possible to install the newer version of the Office 365 suite - see "Installing The Newer Office 365 Suite" below, the alternative is to use Outlook for the Web i.e. Webmail via https://portal.office.com.

Review the following for more information:

Deprecation of Basic authentication in Exchange Online

Installing The Newer Office 365 Suite

Note that you may be able to upgrade a Business Basic licence to Business Standard to obtain the newer software of the Office 365 suite to install on the local computer.

As of writing at November 2022, the following minimum versions of Operating Systems are required to install the newer Office 365 suite:

Windows 8.1
- End-of-life for Windows 8.1 is 10th January 2023.
- It is likely that at this time - or sometime shortly later, the Office 365 software will no longer be supported on that version of Windows.
mac OS Big Sur [11]
- The latest three major releases of the Mac OS are supported for installation.
- The October 2022 update (16.66) of the Office 365 software is the last build to support macOS Catalina [10.15]; it will no longer receive on-going updates.

Please note that while the Office 365 software may well be installable on older operating systems the software would no longer be supported [by Microsoft] - nor will it be updated with security/bug fixes or improvements. It may also be a case that the software will not connect/interface with all or some of the Office 365 systems.

Effectively, the Office 365 software in use in this scenario is at-your-own-risk and cannot be supported nor can issues be troubleshooted - with those out-of-date versions, or when in use on un-supported operating systems.