iOS Mail: Mailbox Management

Using: iPad 4 w/wi-fi; iOS 8.2

I do not understand how the Mailboxes work.

FIrst, I have two Trash mailboxes: one, Trash can, and one, Trash folder.

I also have a mailbox named, Bulk Mail.

None of these three folders did I set up; they came with the Mail app. In OS X, if I wanted a Trash folder or a Bulk Mail box, I would have to manually set them up.

The problem(s):

1. The Trash folder receives mail from my Inbox - NOT PUT THERE BY ME! If I MOVE it back to the Inbox, sometime later it is back in the Trash folder. Currently, I have 76 emails in my Trash folder - that's another problem; if I want to delete them, I have to manually select them ONE AT A TIME - unlike the Trash can which allows deleting all at once. I would like to DELETE THE TRASH FOLDER, but then if Mail decides to move emails from the Inbox without my permission, WHERE WOULD THE EMAILS GO?

2. The Bulk Mail folder also receives mail that should be coming into only my Inbox. My desktop Mac, with the same email account, receives the same emails into its Inbox and thankfully leaves them there.

This automatic switching of emails from the Inbox to the Trash folder or to the Bulk Mail box is frustrating to say the least. When I go to the "iPad User Guide," there is no help for Mail Mailbox management; write, finish, work with, and print messages but no MAILBOX MANAGEMENT HELP!

Please instruct me or send me to a tutorial on iOS Mail's mailbox management.

Thanks,

bob