[log in to unmask] said:

> We noticed that there was no particular order in how those files were
> being acted on.  That is, we noticed newly arriving messages being
> processed before the older mail was.  This seems "wrong" to us (just
> our opinion).

They are processed in physical directory order.  I.e. the order
of the entries in directory when read as a file.  The directory
is not kept in collating order.  ls and such sort things before
they display them.  When a new file comes in it's put in the
first available directory slot.

Glenn