3.7.1 Turning Off New Outlook

The Microsoft Outlook app can run in two modes: Legacy Outlook and New Outlook. SpamSieve uses AppleScript to communicate with Outlook, which is currently only supported in the legacy mode. Microsoft is ending support for Legacy Outlook on November 1, 2026. There’s more information about this, and how it affects SpamSieve, in the End of Support for Legacy Outlook section of the manual.

To switch to legacy mode, in Outlook, click on the Outlook menu at the top of the screen and make sure that Legacy Outlook is checked or that New Outlook is unchecked:

outlook new outlook

In some versions of Outlook, there is no switch to turn off “New Outlook” once it is enabled. You can enter this command in the Terminal app:

defaults write com.microsoft.Outlook EnableNewOutlook 1

and press Return to show the switch. You can also enter this command:

defaults write com.microsoft.Outlook IsRunningNewOutlook NO

to directly turn off New Outlook.

Note that the old and new versions of Outlook have separate mail storage. Messages stored in On My Computer folders will not automatically sync between the two versions.