emclient failing to download mails from btinternet

I have been getting this error for the last 24 hours.  Any ideas as to the cause?

Please see https://forum.emclient.com/emclient/topics/emclient-is-not-downloading-email-from-bt

I have now read the thread with other people reporting the same issue.  Should have read that first.  Please ignore this one.  Sorry.