I snipped most parts of Sam's mail because I covered most of that already (in doubt, the most complete coverage is on the qmail mailing list), and it seems Sam's an my opinions on the problem are congruent.

Sam Varshavchik <mrs...@courier-mta.com> writes:

I beg to differ on this part.

As several others have already pointed out, this will only postpone the problem for some time and for slower machines, but not solve it.

In case you've missed it, I'll repeat my suggestion: I suggested keeping the tmp/timestamp.pid.hostname files for a finite amount of time after linking them to new/ (so that for 20 seconds or 2 seconds or what timeout you choose, both file names exist) -- the tmp/ is then a kind of a lock file that prevents the collision: no application except the one that delivers will ever move stuff out of tmp/, and the additional link will only be unlinked after there is no longer a danger of collision.

Some 16-processor machine with huge caches might have a real problem sooner than we want...