I mean another application than Thunderbird is adding new mails to the mailbox. Which is the classical purpose of a mailbox. In my test Thunderbird had not reco

I mean another application than Thunderbird is adding new mails to the mailbox. Which is the classical purpose of a mailbox. In my test Thunderbird had not recognized the new mails, and I'm not sure whether I just did something wrong, or Thunderbird does not have this ability anymore. After all, they don't offer local mailboxes in their account-settings anymore.