+PP/17 OpenSSL: new expansion var $tls_sni, which if used in tls_certificate
+ lets Exim select keys and certificates based upon TLS SNI from client.
+ Also option tls_sni on SMTP Transports. Also clear $tls_bits correctly
+ before an outbound SMTP session. New log_selector, +tls_sni.
+
+PP/18 Bugzilla 1122 - check localhost_number expansion for failure, avoid
+ NULL dereference. Report and patch from Alun Jones.
+
+PP/19 DNS resolver init changes for NetBSD compatibility. (Risk of breakage
+ on less well tested platforms). Obviates NetBSD pkgsrc patch-ac.
+ Not seeing resolver debug output on NetBSD, but suspect this is a
+ resolver implementation change.
+
+PP/20 Revert part of NM/04, it broke log_path containing %D expansions.
+ Left warnings. Added "eximon gdb" invocation mode.
+
+PP/21 Defaulting "accept_8bitmime" to true, not false.
+
+PP/22 Added -bw for inetd wait mode support.
+
+PP/23 Added PCRE_CONFIG=yes support to Makefile for using pcre-config to
+ locate the relevant includes and libraries. Made this the default.
+
+PP/24 Fixed headers_only on smtp transports (was not sending trailing dot).
+ Bugzilla 1246, report and most of solution from Tomasz Kusy.
+
+JH/03 ${eval } now uses 64-bit and supports a "g" suffix (like to "k" and "m").
+ This may cause build issues on older platforms.
+
+PP/25 Revamped GnuTLS support, passing tls_require_ciphers to
+ gnutls_priority_init, ignoring Exim options gnutls_require_kx,
+ gnutls_require_mac & gnutls_require_protocols (no longer supported).
+ Added SNI support via GnuTLS too.
+ Made ${randint:..} supplier available, if using not-too-old GnuTLS.
+
+PP/26 Added EXPERIMENTAL_OCSP for OpenSSL.
+
+PP/27 Applied dnsdb SPF support patch from Janne Snabb.
+ Applied second patch from Janne, implementing suggestion to default
+ multiple-strings-in-record handling to match SPF spec.
+
+JH/04 Added expansion variable $tod_epoch_l for a higher-precision time.
+
+PP/28 Fix DCC dcc_header content corruption (stack memory referenced,
+ read-only, out of scope).
+ Patch from Wolfgang Breyha, report from Stuart Northfield.
+
+PP/29 Fix three issues highlighted by clang analyser static analysis.
+ Only crash-plausible issue would require the Cambridge-specific
+ iplookup router and a misconfiguration.
+ Report from Marcin Mirosław.
+
+PP/30 Another attempt to deal with PCRE_PRERELEASE, this one less buggy.
+
+PP/31 %D in printf continues to cause issues (-Wformat=security), so for
+ now guard some of the printf checks behind WANT_DEEPER_PRINTF_CHECKS.
+ As part of this, removing so much warning spew let me fix some minor
+ real issues in debug logging.
+
+PP/32 GnuTLS was always using default tls_require_ciphers, due to a missing
+ assignment on my part. Fixed.
+
+PP/33 Added tls_dh_max_bits option, defaulting to current hard-coded limit
+ of NSS, for GnuTLS/NSS interop. Problem root cause diagnosis by
+ Janne Snabb (who went above and beyond: thank you).
+
+PP/34 Validate tls_require_ciphers on startup, since debugging an invalid
+ string otherwise requires a connection and a bunch more work and it's
+ relatively easy to get wrong. Should also expose TLS library linkage
+ problems.
+
+PP/35 Pull in <features.h> on Linux, for some portability edge-cases of
+ 64-bit ${eval} (JH/03).
+
+PP/36 Define _GNU_SOURCE in exim.h; it's needed for some releases of
+ GNU libc to support some of the 64-bit stuff, should not lead to
+ conflicts. Defined before os.h is pulled in, so if a given platform
+ needs to override this, it can.
+
+PP/37 Unbreak Cyrus SASL auth: SSF retrieval was incorrect, Exim thought
+ protection layer was required, which is not implemented.
+ Bugzilla 1254, patch from Wolfgang Breyha.
+
+PP/38 Overhaul DH prime handling, supply RFC-specified DH primes as built
+ into Exim, default to IKE id 23 from RFC 5114 (2048 bit). Make
+ tls_dhparam take prime identifiers. Also unbreak combination of
+ OpenSSL+DH_params+TLSSNI.
+
+PP/39 Disable SSLv2 by default in OpenSSL support.
+
+PP/40 Lower default size of EXIM_CLIENT_DH_MIN_BITS constant (used only by
+ GnuTLS at this time) from 1024 to 512. Cautious folk can override
+ in Local/Makefile.
+