What's the difference between i.e. and e.g.?
A term used to denote mail sent via the traditional postal service, usually to contrast that process to e-mail.
Mail sent through regular postal service: Acrobat has the potential to pay for itself rather quickly by eliminating the need to send documents by courier or even regular mail (snail mail, as it is charmingly called by computer aficionados)
[1980s+ Computer; referring to the slowness of the snail]