[exim] Getting the latest version for Debian Wheezy

I'm using Debian Wheezy at the moment. The latest version for exim
seems to be 4.80 for wheezy. 4.82.1 is available for Jessie (the next
future version of Debian). However, sucking that into wheezy looks
problematic because it also means sucking in a lot of other dependencies
from Jessie.

Does anyone on this list know what the state of getting 4.82.1 (or
whatever is latest) into the backports repository for Debian is? It
seems like this is quite urgent as there are some serious sounding
security fixes since 4.80!

Or is there some other source out there that has the latest exim for
wheezy that I could add to my sources.list file?

Out of curiosity, what version of unix/linux is exim developed on anyway?

Michael Grant