[eschwartz]

I believe calibre is fine with either case -- although not all programs do this, so a wise move is to define all proxy variables twice. For instance, curl requires lowercase, and apt requires uppercase. I think.

Whatever. The point is, it's arbitrary.

Just a general heads-up. calibre may not have problems, other programs will.

The lack of an HTTPS_PROXY (of any case) will, however, definitely fail to proxy all traffic, the instant said traffic switches over to a secured connection.