http://qs1969.pair.com?node_id=470165


in reply to Re^2: Mail::Box fails miserably when trying to open 30_000 messages maildir
in thread Mail::Box fails miserably when trying to open 30_000 messages maildir

still, it could be reasonable to write simple test script to open that dir and just count:
opendir DIR, "that-dir"; my @files = readdir DIR; # or whatever methos Mail::Box uses print "count is ", $#files+1;
Just to check if perl's readdir is out of question on your current build (with given libc and so on)