Major New Features in Exim release 3.20 
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1. There is now a facility for permitting any user to call Exim with the -f
option and any sender address value. Previously, untrusted users were permitted
only to use -f <>.

2. The autoreply transport now has a new option called once_file_size. If set
greater than zero, it changes the way Exim implements the "once" option.
Instead of using a DBM file to record every recipient it sends to, it uses a
regular file, whose size will never get larger than the given value.

3. Exim can now use the tdb DBM library (http://download.sourceforge.net/tdb)
as an alternative to Berkeley db, ndbm, or GDBM.

4. The aliasfile, forwardfile, and smartuser directors now have an option
called hide_child_in_errmsg. What this does is to prevent Exim from quoting a
child address if it generates a bounce or delay message for it.

5. When Exim is delivering to a set of maildir files, and is required to check
a quota setting, it now looks for a file called maildirfolder in the maildir
directory (alongside new, cur, tmp). If this exists, it assumes the directory
is a maildir++ folder directory, which is one level down from the user's
toplevel mailbox file.

6. The smartuser director may now generate pipe and file deliveries in the
new_address option. Relevant options such as file_transport and forbid_file now
exist (compare aliasfile and forwardfile).

7. By default, Exim verifies only the domain of a remote sender address. There
are occasions where more verification is desirable, and there is now a facility
for additional verification by means of a "callback". This means that Exim
makes an SMTP call to the hosts to which the sender's domain resolves, and
tests the address as the recipient of a bounce message.

8. LDAP changes: (a) The way LDAP returns values for multiple attributes has
been changed to be the same as the NIS+ lookup. (b) There is a new lookup type
called ldapdn, which returns the Distinguished Name of an entry.

9. Only an admin user may now set a debug level greater than 1. This is because
debugging output from lookups may show queries that contain password
information. Also, filter file processing can be seen.

10. The smtp transport now has an option called hosts_max_try, with a default
value of 5. It limits the number of IP addresses that will be tried for any one
delivery.

11. If log_incoming_port is set, the remote port number (separated by a dot) is
added to the IP address of incoming calls in all log entries, and in Received:
header lines.

12. A port number may be specified after the IP address with the -oMa and -bh
command line options.

13. The new headers_rewrite generic transport option allows addresses in header
lines to be rewritten at transport time.

14. While expanding $prohibition_reason to reject a recipient because of an RBL
failure, $rbl_domain contains the name of the RBL domain that caused the
rejection.

15. The "extract" expansion item has been enhanced to have yes/no substrings,
like "if" and "lookup".

16. The forwardfile director has a new option called "data". This option is
mutually exclusive with "file". Its contents are expanded, and then used as the
list of forwarding items, or as a set of filtering instructions, just as if
they were the contents of the file.

17. There is now support for LMTP, either using a pipe to another process, or
over TCP/IP.

18. When compiled with IPv6 support, Exim now has code to look for A6 records
in the DNS as well as for AAAA records.

19. prohibition_message wasn't being used after a receiver verify failure (it
was after a sender verify failure). It now is, with reason "receiver_verify".

20. If an option setting is preceded by "hide", it is displayed by the -bP
option only to admin users.

21. Support for TLS (Transport Layer Security), otherwise known as SSL (Secure
Sockets Layer) has been added to this testing release. It is implemented by
making use of the OpenSSL library.

22. If quota_is_inclusive is set false in an appendfile transport, the check
for exceeding the quota does not include the current message.

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