Unwanted indestructible email folders

In Airmail3 I have three Yammer folders in my Exchange / Office 365 account which cannot be deleted. I suspect they were put into my Exchange set up when, as a business, we used Yammer some 8 years ago!

They are only detectable in Airmail but the app’s developers have no constructive advice and simply point the finger at the [Exchange] server. Critically, the folders are not in Office 365 web app. Neither are they in the other email clients I use: Apple Mail, Outlook and Spark.

Any ideas how I can get rid of them?



Once when I couldn’t delete a message I was told that the attachment had to be deleted first.

Thanks - there are actually no emails in these folders.

Looks like this comes up in Apple Mail too, e.g. https://kb.wisc.edu/page.php?id=67718

Interesting. Even for the facist tendencies of M$oft, creating folders you don’t want and can’t delete is remarkably irritating.