scache(8) connection cache server logs statistics about the
peak cache size and the cache hit rates. This information is logged
connection_cache_status_update_time seconds, when the process
terminates after the maximal idle time is exceeded, or when Postfix
Hit rates for connection cache lookups by domain will tell
you how useful connection caching is.
Connection cache lookups by network address will always
fail, unless you're sending mail to different domains that share
the same MX hosts.
No statistics are logged when no attempts are made to
access the connection cache.