serverbug error

A few hours ago, my mail server stopped allowing deletion of items in my inbox with a message that there was an internal error [SERVERBUG].  The message said to refer to the server log for more information.  

I logged into the Cox Email site and also got errors when I tried to delete messages.  The error message response was: 

This message could not be moved to trash folder, possibly because your mailbox is nearly full.
In that case, please try to empty your deleted items first, or delete smaller messages first.  

??