Only use the metaphor
Lots of computer UI and functionality is laid out and described in terms of physical items. We have documents, Files, Folders, etc. I guess with eMail, they are trying to recreate that historical aspect of not knowing accurately when (if) your mail will be delivered. What's the digital equivalent of a piece of mail being sat out in the rain for a couple of days or mangled in the post's sorting machinery?
Biting the hand that feeds IT
