Outlook.com no longer deletes mail (2020-11)

[German]Users of the Microsoft e-mail service outlook.com are currently plagued by an annoying problem. If they delete a mail in their inbox, it will reappear as unread in their inbox shortly afterwards. Here is a brief overview of this issue and the question of who is affected.

I recently reported about an issue with Microsoft's online services (see Microsoft Store, Outlook und Xbox Live worldwide down (Nov. 10, 2020)). German blogger Martin Geuß also briefly touched this topic with an article. There I saw several comment like this show below from German readers:

Since days I get my recently deleted mails as "unread" in my inbox, so that I have to delete all old mails after every new mail that comes in.

Other users have confirmed exactly this problem in the comments. User Soernesto writes that the problem exists since a few days, especially with a connected external account. At the same time blog-reader Martin B. asked me yesterday evening by mail about this issue:

you could blog the topic / problem. I have already commented the portal's post accordingly and I bet there are tens of affected users in DACH, too. I have already tried in vain to google the problem, – so far without result. Remedy is indeed the permanent deletion of the mails directly in the accounts – cumbersome!

Bleeping Computer had already addressed the issue in this article on November 10, 2020 – I didn't have the time to discuss it here in the blog. The article probably picks up the Microsoft support post titled Emails deleted from Outlook.com are reverting back to the Inbox from the same day. There Microsoft confirms the error and writes::

ISSUE

Users with Outlook.com accounts are seeing emails they delete from the Inbox reverting back to the Inbox.

STATUS: INVESTIGATING

The Outlook Team is investigating the issue for a fix. We will update this article as soon as we have more information on a fix.

This Outlook.com support document provides a proposal for a workaround:

In the meantime, if the emails being reverted are coming from connected accounts you may be able to go to the Inbox of the originating account and delete the email to workaround the issue.  For example, if you have a Gmail connected account, go to Gmail.com and delete the email from there.

Let's hope that the outlook.com team quickly finds a fix for this annoying issue. Somebody affected?