Log Message:
exim: updated to 4.91

Version 4.91

 1. Dual-certificate stacks on servers now support OCSP stapling, under GnuTLS
    version 3.5.6 or later.

 2. DANE is now supported under GnuTLS version 3.0.0 or later.  Both GnuTLS and
    OpenSSL versions are moved to mainline support from Experimental.
    New SMTP transport option "dane_require_tls_ciphers".

 3. Feature macros for the compiled-in set of malware scanner interfaces.

 4. SPF support is promoted from Experimental to mainline status.  The template
    src/EDITME makefile does not enable its inclusion.

 5. Logging control for DKIM verification.  The existing DKIM log line is
    controlled by a "dkim_verbose" selector which is _not_ enabled by \ 
default.
    A new tag "DKIM=<domain>" is added to <= lines by \ 
default, controlled by
    a "dkim" log_selector.

 6. Receive duration on <= lines, under a new log_selector \ 
"receive_time".

 7. Options "ipv4_only" and "ipv4_prefer" on the dnslookup \ 
router and on
    routing rules in the manualroute router.

 8. Expansion item ${sha3:<string>} / ${sha3_<N>:<string>} now \ 
also supported
    under OpenSSL version 1.1.1 or later.

 9. DKIM operations can now use the Ed25519 algorithm in addition to RSA, under
    GnuTLS 3.6.0 or OpenSSL 1.1.1 or later.

10. Builtin feature-macros _CRYPTO_HASH_SHA3 and _CRYPTO_SIGN_ED25519, library
    version dependent.

11. "exim -bP macro <name>" returns caller-usable status.

12. Expansion item ${authresults {<machine>}} for creating an
    Authentication-Results: header.

13. EXPERIMENTAL_ARC.  See the experimental.spec file.
    See also new util/renew-opendmarc-tlds.sh script for use with DMARC/ARC.

14: A dane:fail event, intended to facilitate reporting.

15. "Lightweight" support for Redis Cluster. Requires redis_servers list to
    contain all the servers in the cluster, all of which must be reachable from
    the running exim instance. If the cluster has master/slave replication, the
    list must contain all the master and slave servers.

16. Add an option to the Avast scanner interface: "pass_unscanned". This
    allows to treat unscanned files as clean. Files may be unscanned for
    several reasons: decompression bombs, broken archives.