All e-mails deleted?

I recently purchased a smart phone and decided I didn't need to have all my in box messages on the phone, so I deleted them.  When I went into my laptop to check my e-mail, all my messages had been deleted from the laptop as well.  I checked my desktop IMac and all messages were deleted form there too.  I went to the server to read a couple of messages I had not read, only to find out that all me mail on the server had been deleted!  What's happening?  Do I have to leave all messages in all inboxes in order to have access to them from any device?