As the system matures you will undoubtedly see more and more folders pop up. It is a special 'attention getting' technique. No matter how irritating or confusing you may find it, there is no way to change it. For the simple reason that email takes up disk space, which on some computers is quite limited. For instance, a certain Language Arts teacher at SCMS racked up over 50 Megabytes of emails last year.
Disk space costs money.
If you get an email that is important and you do not want it to be deleted you must set it to not expire. A screen will pop up. Set the expiration date to 'Never Expire'. 13 Play around, get it to suit your taste by trying out the different image choices other than 'Default'. You may also add your own images and background patterns if you wish.