Log Message:
postfix: Update to 3.4.7

upstream changes:
-----------------
* Robustness: the tlsproxy(8) daemon could go into a loop, logging a flood of
  error messages. Problem reported by Andreas Schulze after enabling SMTP/TLS
  connection reuse.
* Workaround: OpenSSL changed an SSL_Shutdown() non-error result value into an
  error result value, causing logfile noise.
* Configuration: the new 'TLS fast shutdown' parameter name was implemented
  incorrectly. The documentation said "tls_fast_shutdown_enable", but \ 
the code
  said "tls_fast_shutdown". This was fixed by changing the code, \ 
because no-one
  is expected to override the default.
* Performance: workaround for poor TCP loopback performance on LINUX, where
  getsockopt(..., TCP_MAXSEG, ...) reports a bogus TCP maximal segment size that
  is 1/2 to 1/3 of the real MSS. To avoid client-side Nagle delays or
  server-side delayed ACKs caused by multiple smaller-than-MSS writes, Postfix
  chooses a VSTREAM buffer size that is a small multiple of the reported bogus
  MSS. This workaround increases the multiplier from 2x to 4x.
* Robustness: the Postfix Dovecot client could segfault (null pointer read) or
  cause an SMTP server assertion to fail when talking to a fake Dovecot server.
  The Postfix Dovecot client now logs a proper error instead. Problem reported
  by Tim Düsterhus.