+JH/28 Bug 2996: Fix a crash in the smtp transport. When finding that the
+ message being considered for delivery was already being handled by
+ another process, and having an SMTP connection already open, the function
+ to close it tried to use an uninitialized variable. This would afftect
+ high-volume sites more, especially when running mailing-list-style loads.
+ Pollution of logs was the major effect, as the other process delivered
+ the message. Found and partly investigated by Graeme Fowler.
+
+JH/29 Change format of the internal ID used for message identification. The old
+ version only supported 31 bits for a PID element; the new 64 (on systems
+ which can use Base-62 encoding, which is all currently supported ones
+ but not Darwin (MacOS) or Cygwin, which have case-insensitive filesystems
+ and must use Base-36). The new ID is 23 characters rather than 16, and is
+ visible in various places - notably logs, message headers, and spool file
+ names. Various of the ancillary utilities also have to know the format.
+ As well as the expanded PID portion, the sub-second part of the time
+ recorded in the ID is expanded to support finer precision. Theoretically
+ this permits a receive rate from a single comms channel of better than the
+ previous 2000/sec.
+ The major timestamp part of the ID is not changed; at 6 characters it is
+ usable until about year 3700.
+ Updating from previously releases is fully supported: old-format spool
+ files are still usable, and the utilities support both formats. New
+ message will use the new format. The one hints-DB file type which uses
+ message-IDs (the transport wait- DB) will be discarded if an old-format ID
+ is seen; new ones will be built with only new-format IDs.
+ Optionally, a utility can be used to convert spool files from old to new,
+ but this is only an efficiency measure not a requirement for operation
+ Downgrading from new to old requires running a provided utility, having
+ first stopped all operations. This will convert any spool files from new
+ back to old (losing time-precision and PID information) and remove any
+ wait- hints databases.
+
+JH/30 Bug 3006: Fix handling of JSON strings having embedded commas. Previously
+ we treated them as item separators when parsing for a list item, but they
+ need to be protected by the doublequotes. While there, add handling for
+ backslashes.
+
+JH/31 Bug 2998: Fix ${utf8clean:...} to disallow UTF-16 surrogate codepoints.
+ Found and fixed by Jasen Betts. No testcase for this as my usual text
+ editor insists on emitting only valid UTF-8.
+
+JH/32 Fix "tls_dhparam = none" under GnuTLS. At least with 3.7.9 this gave
+ a null-indirection SIGSEGV for the receive process.
+
+JH/33 Fix free for live variable $value created by a ${run ...} expansion during
+ -bh use. Internal checking would spot this and take a panic.
+
+JH/34 Bug 3013: Fix use of $recipients within arguments for ${run...}.
+ In 4.96 this would expand to empty.
+
+JH/35 Bug 3014: GnuTLS: fix expiry date for an auto-generated server
+ certificate. Find and fix by Andreas Metzler.
+
+JH/36 Add ARC info to DMARC hostory records.
+
+JH/37 Bug 3016: Avoid sending DSN when message was accepted under fakereject
+ or fakedefer. Previously the sender could discover that the message
+ had in fact been accepted.
+