When HostStatusDirectory is enabled, information about the
status of hosts is maintained on disk and can thus be shared between
different instantiations of
sendmail(1M).
The status of the last connection with each remote host may be viewed
with the command:
sendmail -bh
This information may be flushed with the command:
sendmail -bH
Flushing the information prevents new sendmail processes from loading it, but does not prevent existing processes from using the status information that they already have.