IMAP integration always "Unknown" with Outlook/Hotmail account

[Didgeridrew]

The problem

IMAP integration fails to give number of unread emails for Outlook/Hotmail accounts only. Gmail works as expected.

What is version of Home Assistant Core has the issue?

core-2021.3.4

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant OS

Integration causing the issue

IMAP

Link to integration documentation on our website

https://www.home-assistant.io/integrations/imap/

Example YAML snippet

sensor:
- platform: imap
  name: dj_hotmail
  server: outlook.office365.com
  port: 993
  username: !secret dj_hotmail
  password: !secret dj_hotmail_pw

Anything in the logs that might be useful for us?

Logger: homeassistant.components.imap.sensor
Source: components/imap/sensor.py:164
Integration: imap (documentation, issues)
First occurred: 1:09:22 PM (2 occurrences)
Last logged: 1:09:22 PM

Can't parse IMAP server response to search 'UnSeen UnDeleted': NO / [BADCHARSET (US-ASCII)] The specified charset is not supported.

I tried the solution from #20642, but that just caused further errors.

[probot-home-assistant]

imap documentation
imap source
_{^{(message by IssueLinks)}}

[github-actions]

There hasn't been any activity on this issue recently. Due to the high number of incoming GitHub notifications, we have to clean some of the old issues, as many of them have already been resolved with the latest updates.
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This issue has now been marked as stale and will be closed if no further activity occurs. Thank you for your contributions.