[Exim] exim & qpopper info

hello eximmers,

how do exim and pop servers in general (qpopper in particular) interact?
what is the locking strategy? I found this in an usenet post:

someone wrote:
> [snip] or otherwise stops his pop3 daemon while it is actively trying
> to communicate with exim.

..so it looks like it is more than just a "locking strategy" but I can't
find any further info!

sorry for the FAQ.. actually I wonder if it *really is* a FAQ since
feeding dejanews with "exim qpopper lock*" shows nothing relevant..

TIA!

--
Otavio Exel /<\oo/>\ oexel@???