+PH/50 When an Exim quota was set without a file count quota, and mailbox_size
+ was also set, the appendfile transport was unnecessarily scanning a
+ directory of message files (e.g. for maildir delivery) to find the count
+ of files (along with the size), even though it did not need this
+ information. It now does the scan only if it needs to find either the
+ size of the count of files.
+
+PH/51 Added ${time_eval: to convert Exim time strings into seconds.
+
+PH/52 Two bugs concerned with error handling when the smtp transport is
+ used in LMTP mode:
+
+ (i) Exim was not creating retry information for temporary errors given
+ for individual recipients after the DATA command when the smtp transport
+ was used in LMTP mode. This meant that they could be retried too
+ frequently, and not timed out correctly.
+
+ (ii) Exim was setting the flag that allows error details to be returned
+ for LMTP errors on RCPT commands, but not for LMTP errors for individual
+ recipients that were returned after the DATA command.
+
+PH/53 This is related to PH/52, but is more general: for any failing address,
+ when detailed error information was permitted to be returned to the
+ sender, but the error was temporary, then after the final timeout, only
+ "retry timeout exceeded" was returned. Now it returns the full error as
+ well as "retry timeout exceeded".
+
+PH/54 Added control=allow_auth_unadvertised, as it seems there are clients that
+ do this, and (what is worse) MTAs that accept it.
+