improper unlinks

[Eugene Crosser <crosser@online.ru>]

Matti,

BTW when I inserted checks before unlinks performed by router and scheduler,
I noticed that zunlink() (function that removes file in the router directory)
is called many, *many* times on non-existing files.  This does not cause
problems like those when eunlink() removes directories, but still it may
be a good idea to clean this up...

And Matti, did you have a chance to check what goes wrong when multiline
Return-Receipt-To: is processed (apparently the case that triggers
directory removal)?

Eugene