IMAP Cannot open folder Internal error Try again later


I have been using eM Client for several months now, without any problems. I even used it today in the afternoon and everything was OK. Then in the evening I started getting dozens of error messages (see attached image) every time I want to switch to a different folder. When I click on Outbox/Unread/Flagged etc., the window with the error messages pops up. 

Obviously nothing has changed as far as my hardware or configuration or Internet provider is concerned. When I log into my e-mail from their website, everything works fine.  IMAP is enabled. In other words, nothing has changed anywhere, but eM Client started acting like this. 

Sending and receiving seems to be working, although images are not shown in some emails. I’m not sure if it’s related to the main problem. 

Can anyone help? 

Apparently, this was a problem with my Internet Provider’s servers. The problem disappeared after about 24 hours, so this thread can be closed.