Okay. So, did you take a look at that recent node that I mentioned earlier? If I read it right, I think it says that if you put the "child" portion of your code into an eval block, it will behave better:

sub qmail_requeue {

   ...
    my $pid = fork;
   ...
    if (not defined $pid) {
      &tempfail ("Unable to fork. (#4.3.0) - $!");
    } elsif ($pid == 0) {
      # In child.  PUT THIS PART IN AN EVAL BLOCK
      eval {
        close EIN;
        ...
      }
    } else { # in parent
   ...
[download]

But as I mentioned in one of my replies on that other thread, I am (like you) not conversant with using fork from within an eval block -- check that thread for yourself, and good luck!