I have connected three external emails channels we want to monitor for our CS project in JSM (not via Google, or Microsoft). The e-mail channels are hosted by Thunderbird.
I have connected them via IMAPS and it was no problem to add them.
But after adding them, I received a warning that there is an issue within the project and all three connected emails are not working properly. This is the connectivity log displayed for all three emails:

When I navigated to Settings -> Product -> Email request and used the "test" Action, I got the response "No problems found with email settings configuration.".
Does anyone have any idea what the problem could be and how to resolve it?