+JH/15 When PIPELINING, synch after every hundred or so RCPT commands sent and
+ check for 452 responses. This slightly helps the inefficieny of doing
+ a large alias-expansion into a recipient-limited target. The max_rcpt
+ transport option still applies (and at the current default, will override
+ the new feature). The check is done for either cause of synch, and forces
+ a fast-retry of all 452'd recipients using a new MAIL FROM on the same
+ connection. The new facility is not tunable at this time.
+
+JH/16 Fix the variables set by the gsasl authenticator. Previously a pointer to
+ library live data was being used, so the results became garbage. Make
+ copies while it is still usable.
+
+JH/17 Logging: when the deliver_time selector ise set, include the DT= field
+ on delivery deferred (==) and failed (**) lines (if a delivery was
+ attemtped). Previously it was only on completion (=>) lines.
+
+JH/18 Authentication: the gsasl driver not provides the $authN variables in time
+ for the expansion of the server_scram_iter and server_scram_salt options.
+
+WB/01 SPF: DNS lookups for the obsolete SPF RR type done by the libspf2 library
+ are now specifically given a NO_DATA response without hitting the system
+ resolver. The library goes on to do the now-standard TXT lookup.
+ Use of dnsdb lookups is not affected.
+
+JH/19 Bug 2507: Modules: on handling a dynamic-module (lookups) open failure,
+ only retrieve the errormessage once. Previously two calls to dlerror()
+ were used, and the second one (for mainlog/paniclog) retrieved null
+ information.
+
+JH/20 Taint checking: disallow use of tainted data for
+ - the appendfile transport file and directory options
+ - the pipe transport command
+ - the autoreply transport file, log and once options
+ - file names used by the redirect router (including filter files)
+ - named-queue names
+ Previously this was permitted.
+
+JH/21 Bug 2501: Fix init call in the heimdal authenticator. Previously it
+ adjusted the size of a major service buffer; this failed because the
+ buffer was in use at the time. Change to a compile-time increase in the
+ buffer size, when this authenticator is compiled into exim.
+
+JH/22 Taint-checking: move to safe-mode taint checking on all platforms. The
+ previous fast-mode was untenable in the face of glibs using mmap to
+ support larger malloc requests.
+
+PP/01 Update the openssl_options possible values through OpenSSL 1.1.1c.
+ New values supported, if defined on system where compiled:
+ allow_no_dhe_kex, cryptopro_tlsext_bug, enable_middlebox_compat,
+ no_anti_replay, no_encrypt_then_mac, prioritize_chacha, tlsext_padding
+
+JH/23 Performance improvement in the initial phase of a two-pass queue run. By
+ running a limited number of proceses in parallel, a benefit is gained. The
+ amount varies with the platform hardware and load. The use of the option
+ queue_run_in_order means we cannot do this, as ordering becomes
+ indeterminate.
+
+JH/24 Bug 2524: fix the cyrus_sasl auth driver gssapi usage. A previous fix
+ had introduced a string-copy (for ensuring NUL-termination) which was not
+ appropriate for that case, which can include embedded NUL bytes in the
+ block of data. Investigation showed the copy to actually be needless, the
+ data being length-specified.
+
+JH/25 Fix use of concurrent TLS connections under GnuTLS. When a callout was
+ done during a receiving connection, and both used TLS, global info was
+ used rather than per-connection info for tracking the state of data
+ queued for transmission. This could result in a connection hang.
+
+JH/26 Fix use of the SIZE parameter on MAIL commands, on continued connections.
+ Previously, when delivering serveral messages down a single connection
+ only the first would provide a SIZE. This was due to the size information
+ not being properly tracked.
+
+JH/27 Bug 2530: When operating in a timezone with sub-minute offset, such as
+ TAI (at 37 seconds currently), pretend to be in UTC for time-related
+ expansion and logging. Previously, spurious values such as a future
+ minute could be seen.
+
+JH/28 Bug 2533: Fix expansion of ${tr } item. When called in some situations
+ it could crash from a null-deref. This could also affect the
+ ${addresses: } operator and ${readsock } item.
+