How do i stop emails automatically moving from inbox to trash without being read

Using EM Client with a BT email address. When i receive emails they land in my inbox but within approx 10-20 seconds whether or not the email is read or opened they automatically move into the Trash folder. This is happening with ever email so my inbox is empty but the trash folder is full on unread emails. PLEASE HELP!!!

Is this still happening?

Thanks Gary, appreciate the reply and suggestion. Just got in so not had time to follow up on your suggestion. Will let you know.

Hi Gary,

Heads up after a lot of playing about and talking to BT Yahoo. The problem is sorted but yes it was occurring on the Yahoo platform however, it transpires it was Gmail was the culprit. My wife had had this set up on her laptop and new iPhone and something somewhere within was causing havoc. Removed Gmail or at least removed the BT Internet email from Gmail and everything went back to working. Happy days. 

Thanks again.