from Wietse:
People, if you run the trace-2001209 code, please edit master.cf,
and set a 1 in the verify server process limit field, then "postfix
reload".
Bad: verify unix - - n - 0 verify
Good: verify unix - - n - 1 verify
================
Len: this prevents more than one process, and the observed problem of
giving a positive result from one verify process, followed a negative
result by another verify process, for the same sender_address.
Len
