Yahoo deleting emails from by sbcglobal account
I still have an sbcglobal email address that I access through yahoo.com. From time to time my older emails automatically get moved to my trash folder. Why is this happening????? I save those emails for a reason. I don't have a million emails in my inbox. At any one time I only have about 20. Is there some limit to emails in your inbox? How can I stop this fem happening?