-# $Cambridge: exim/src/src/EDITME,v 1.18 2006/12/05 11:35:28 ph10 Exp $
-
##################################################
# The Exim mail transport agent #
##################################################
# group that is used for Exim processes when they no longer need to be root. In
# particular, this applies when receiving messages and when doing remote
# deliveries. (Local deliveries run as various non-root users, typically as the
-# owner of a local mailbox.) Specifying these values as root is very strongly
-# discouraged.
+# owner of a local mailbox.) Specifying these values as root is not supported.
EXIM_USER=
# SUPPORT_MBX=yes
+#------------------------------------------------------------------------------
+# See below for dynamic lookup modules.
+#
+# If not using package management but using this anyway, then think about how
+# you perform upgrades and revert them. You should consider the benefit of
+# embedding the Exim version number into LOOKUP_MODULE_DIR, so that you can
+# maintain two concurrent sets of modules.
+#
+# *BEWARE*: ability to modify the files in LOOKUP_MODULE_DIR is equivalent to
+# the ability to modify the Exim binary, which is often setuid root! The Exim
+# developers only intend this functionality be used by OS software packagers
+# and we suggest that such packagings' integrity checks should be paranoid
+# about the permissions of the directory and the files within.
+
+# LOOKUP_MODULE_DIR=/usr/lib/exim/lookups/
+
+# To build a module dynamically, you'll need to define CFLAGS_DYNAMIC for
+# your platform. Eg:
+# CFLAGS_DYNAMIC=-shared -rdynamic
+# CFLAGS_DYNAMIC=-shared -rdynamic -fPIC
+
#------------------------------------------------------------------------------
# These settings determine which file and database lookup methods are included
# in the binary. See the manual chapter entitled "File and database lookups"
# LOOKUP_DNSDB does *not* refer to general mail routing using the DNS. It is
# for the specialist case of using the DNS as a general database facility (not
# common).
+# If set to "2" instead of "yes" then the corresponding lookup will be
+# built as a module and must be installed into LOOKUP_MODULE_DIR. You need to
+# add -export-dynamic -rdynamic to EXTRALIBS. You may also need to add -ldl to
+# EXTRALIBS so that dlopen() is available to Exim. You need to define
+# LOOKUP_MODULE_DIR above so the exim binary actually loads dynamic lookup
+# modules.
+# Also, instead of adding all the libraries/includes to LOOKUP_INCLUDE and
+# LOOKUP_LIBS, add them to the respective LOOKUP_*_INCLUDE and LOOKUP_*_LIBS
+# (where * is the name as given here in this list). That ensures that only
+# the dynamic library and not the exim binary will be linked against the
+# library.
+# NOTE: LDAP cannot be built as a module!
+#
+# For Redis you need to have hiredis installed on your system
+# (https://github.com/redis/hiredis).
+# Depending on where it is installed you may have to edit the CFLAGS
+# (often += -I/usr/local/include) and LDFLAGS (-lhiredis) lines.
+
+# If your system has pkg-config then the _INCLUDE/_LIBS setting can be
+# handled for you automatically by also defining the _PC variable to reference
+# the name of the pkg-config package, if such is available.
LOOKUP_DBM=yes
LOOKUP_LSEARCH=yes
+LOOKUP_DNSDB=yes
# LOOKUP_CDB=yes
-# LOOKUP_DNSDB=yes
# LOOKUP_DSEARCH=yes
# LOOKUP_IBASE=yes
# LOOKUP_LDAP=yes
# LOOKUP_ORACLE=yes
# LOOKUP_PASSWD=yes
# LOOKUP_PGSQL=yes
+# LOOKUP_REDIS=yes
# LOOKUP_SQLITE=yes
+# LOOKUP_SQLITE_PC=sqlite3
# LOOKUP_WHOSON=yes
# These two settings are obsolete; all three lookups are compiled when
# Michigan (OpenLDAP 1) library.
+#------------------------------------------------------------------------------
+# The PCRE library is required for Exim. There is no longer an embedded
+# version of the PCRE library included with the source code, instead you
+# must use a system library or build your own copy of PCRE.
+# In either case you must specify the library link info here. If the
+# PCRE header files are not in the standard search path you must also
+# modify the INCLUDE path (above)
+#
+# Use PCRE_CONFIG to query the pcre-config command (first found in $PATH)
+# to find the include files and libraries, else use PCRE_LIBS and set INCLUDE
+# too if needed.
+
+PCRE_CONFIG=yes
+# PCRE_LIBS=-lpcre
+
+
#------------------------------------------------------------------------------
# Additional libraries and include directories may be required for some
# lookup styles (e.g. LDAP, MYSQL or PGSQL). LOOKUP_LIBS is included only on
# the command for linking Exim itself, not on any auxiliary programs. You
# don't need to set LOOKUP_INCLUDE if the relevant directories are already
# specified in INCLUDE. The settings below are just examples; -lpq is for
-# PostgreSQL, -lgds is for Interbase, -lsqlite3 is for SQLite.
+# PostgreSQL, -lgds is for Interbase, -lsqlite3 is for SQLite, -lhiredis
+# is for Redis.
+#
+# You do not need to use this for any lookup information added via pkg-config.
# LOOKUP_INCLUDE=-I /usr/local/ldap/include -I /usr/local/mysql/include -I /usr/local/pgsql/include
# LOOKUP_LIBS=-L/usr/local/lib -lldap -llber -lmysqlclient -lpq -lgds -lsqlite3
# WITH_CONTENT_SCAN=yes
-# If you want to use the deprecated "demime" condition in the DATA ACL,
-# uncomment the line below. Doing so will also explicitly turn on the
-# WITH_CONTENT_SCAN option. If possible, use the MIME ACL instead of
-# the "demime" condition.
+#------------------------------------------------------------------------------
+# If you're using ClamAV and are backporting fixes to an old version, instead
+# of staying current (which is the more usual approach) then you may need to
+# use an older API which uses a STREAM command, now deprecated, instead of
+# zINSTREAM. If you need to set this, please let the Exim developers know, as
+# if nobody reports a need for it, we'll remove this option and clean up the
+# code. zINSTREAM was introduced with ClamAV 0.95.
+#
+# WITH_OLD_CLAMAV_STREAM=yes
+
+
+#------------------------------------------------------------------------------
+# If built with TLS, Exim includes code to support DKIM (DomainKeys Identified
+# Mail, RFC4871) signing and verification. Verification of signatures is
+# turned on by default. See the spec for information on conditionally
+# disabling it. To disable the inclusion of the entire feature, set
+# DISABLE_DKIM to "yes"
+
+# DISABLE_DKIM=yes
+
+#------------------------------------------------------------------------------
+# Uncomment the following line to remove Per-Recipient-Data-Response support.
+
+# DISABLE_PRDR=yes
+
+#------------------------------------------------------------------------------
+# Uncomment the following line to remove OCSP stapling support in TLS,
+# from Exim. Note it can only be supported when built with
+# GnuTLS 3.1.3 or later, or OpenSSL
+
+# DISABLE_OCSP=yes
+
+#------------------------------------------------------------------------------
+# By default, Exim has support for checking the AD bit in a DNS response, to
+# determine if DNSSEC validation was successful. If your system libraries
+# do not support that bit, then set DISABLE_DNSSEC to "yes"
+# Note: Enabling EXPERIMENTAL_DANE unconditionally overrides this setting.
+
+# DISABLE_DNSSEC=yes
+
+# To disable support for Events set DISABLE_EVENT to "yes"
+
+# DISABLE_EVENT=yes
-# WITH_OLD_DEMIME=yes
#------------------------------------------------------------------------------
# Compiling Exim with experimental features. These are documented in
# experimental-spec.txt. "Experimental" means that the way these features are
# implemented may still change. Backward compatibility is not guaranteed.
+# Uncomment the following line to add support for talking to dccifd. This
+# defaults the socket path to /usr/local/dcc/var/dccifd.
+# Doing so will also explicitly turn on the WITH_CONTENT_SCAN option.
+
+# EXPERIMENTAL_DCC=yes
+
# Uncomment the following lines to add SPF support. You need to have libspf2
# installed on your system (www.libspf2.org). Depending on where it is installed
# you may have to edit the CFLAGS and LDFLAGS lines.
# CFLAGS += -I/usr/local/include
# LDFLAGS += -lsrs_alt
+# Uncomment the following line to add DMARC checking capability, implemented
+# using libopendmarc libraries. You must have SPF support enabled also.
+# EXPERIMENTAL_DMARC=yes
+# CFLAGS += -I/usr/local/include
+# LDFLAGS += -lopendmarc
+
# Uncomment the following lines to add Brightmail AntiSpam support. You need
# to have the Brightmail client SDK installed. Please check the experimental
# documentation for implementation details. You need to edit the CFLAGS and
# CFLAGS += -I/opt/brightmail/bsdk-6.0/include
# LDFLAGS += -lxml2_single -lbmiclient_single -L/opt/brightmail/bsdk-6.0/lib
+# Uncomment the following line to add DANE support
+# Note: Enabling this unconditionally overrides DISABLE_DNSSEC
+# Note: DANE is only supported when using OpenSSL
+# EXPERIMENTAL_DANE=yes
+# Uncomment the following to include extra information in fail DSN message (bounces)
+# EXPERIMENTAL_DSN_INFO=yes
+
+# Uncomment the following to add LMDB lookup support
+# You need to have LMDB installed on your system (https://github.com/LMDB/lmdb)
+# Depending on where it is installed you may have to edit the CFLAGS and LDFLAGS lines.
+# EXPERIMENTAL_LMDB=yes
+# CFLAGS += -I/usr/local/include
+# LDFLAGS += -llmdb
+
+# Uncomment the following line to add queuefile transport support
+# EXPERIMENTAL_QUEUEFILE=yes
###############################################################################
# THESE ARE THINGS YOU MIGHT WANT TO SPECIFY #
#------------------------------------------------------------------------------
-# By default, Exim insists that its configuration file be owned either by root
-# or by the Exim user. You can specify one additional permitted owner here.
+# By default, Exim insists that its configuration file be owned by root. You
+# can specify one additional permitted owner here.
# CONFIGURE_OWNER=
# If the configuration file is group-writeable, Exim insists by default that it
-# is owned by root or the Exim user. You can specify one additional permitted
-# group owner here.
+# is owned by root. You can specify one additional permitted group owner here.
# CONFIGURE_GROUP=
#------------------------------------------------------------------------------
# The -C option allows Exim to be run with an alternate runtime configuration
-# file. When this is used by root or the Exim user, root privilege is retained
-# by the binary (for any other caller, it is dropped). You can restrict the
-# location of alternate configurations by defining a prefix below. Any file
-# used with -C must then start with this prefix (except that /dev/null is also
-# permitted if the caller is root, because that is used in the install script).
-# If the prefix specifies a directory that is owned by root, a compromise of
-# the Exim account does not permit arbitrary alternate configurations to be
-# used. The prefix can be more restrictive than just a directory (the second
-# example).
+# file. When this is used by root, root privilege is retained by the binary
+# (for any other caller including the Exim user, it is dropped). You can
+# restrict the location of alternate configurations by defining a prefix below.
+# Any file used with -C must then start with this prefix (except that /dev/null
+# is also permitted if the caller is root, because that is used in the install
+# script). If the prefix specifies a directory that is owned by root, a
+# compromise of the Exim account does not permit arbitrary alternate
+# configurations to be used. The prefix can be more restrictive than just a
+# directory (the second example).
# ALT_CONFIG_PREFIX=/some/directory/
# ALT_CONFIG_PREFIX=/some/directory/exim.conf-
#------------------------------------------------------------------------------
-# If you uncomment the following line, only root may use the -C or -D options
-# without losing root privilege. The -C option specifies an alternate runtime
-# configuration file, and the -D option changes macro values in the runtime
-# configuration. Uncommenting this line restricts what can be done with these
-# options. A call to receive a message (either one-off or via a daemon) cannot
-# successfully continue to deliver it, because the re-exec of Exim to regain
-# root privilege will fail, owing to the use of -C or -D by the Exim user.
-# However, you can still use -C for testing (as root) if you do separate Exim
-# calls for receiving a message and subsequently delivering it.
+# When a user other than root uses the -C option to override the configuration
+# file (including the Exim user when re-executing Exim to regain root
+# privileges for local message delivery), this will normally cause Exim to
+# drop root privileges. The TRUSTED_CONFIG_LIST option, specifies a file which
+# contains a list of trusted configuration filenames, one per line. If the -C
+# option is used by the Exim user or by the user specified in the
+# CONFIGURE_OWNER setting, to specify a configuration file which is listed in
+# the TRUSTED_CONFIG_LIST file, then root privileges are not dropped by Exim.
-# ALT_CONFIG_ROOT_ONLY=yes
+# TRUSTED_CONFIG_LIST=/usr/exim/trusted_configs
#------------------------------------------------------------------------------
# DISABLE_D_OPTION=yes
+#------------------------------------------------------------------------------
+# By contrast, you might be maintaining a system which relies upon the ability
+# to override values with -D and assumes that these will be passed through to
+# the delivery processes. As of Exim 4.73, this is no longer the case by
+# default. Going forward, we strongly recommend that you use a shim Exim
+# configuration file owned by root stored under TRUSTED_CONFIG_LIST.
+# That shim can set macros before .include'ing your main configuration file.
+#
+# As a strictly transient measure to ease migration to 4.73, the
+# WHITELIST_D_MACROS value definies a colon-separated list of macro-names
+# which are permitted to be overridden from the command-line which will be
+# honoured by the Exim user. So these are macros that can persist to delivery
+# time.
+# Examples might be -DTLS or -DSPOOL=/some/dir. The values on the
+# command-line are filtered to only permit: [A-Za-z0-9_/.-]*
+#
+# This option is highly likely to be removed in a future release. It exists
+# only to make 4.73 as easy as possible to migrate to. If you use it, we
+# encourage you to schedule time to rework your configuration to not depend
+# upon it. Most people should not need to use this.
+#
+# By default, no macros are whitelisted for -D usage.
+
+# WHITELIST_D_MACROS=TLS:SPOOL
+
#------------------------------------------------------------------------------
# Exim has support for the AUTH (authentication) extension of the SMTP
# protocol, as defined by RFC 2554. If you don't know what SMTP authentication
# AUTH_CRAM_MD5=yes
# AUTH_CYRUS_SASL=yes
# AUTH_DOVECOT=yes
+# AUTH_GSASL=yes
+# AUTH_GSASL_PC=libgsasl
+# AUTH_HEIMDAL_GSSAPI=yes
+# AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi
# AUTH_PLAINTEXT=yes
# AUTH_SPA=yes
+# AUTH_TLS=yes
#------------------------------------------------------------------------------
# If you specified AUTH_CYRUS_SASL above, you should ensure that you have the
# Cyrus SASL library installed before trying to build Exim, and you probably
-# want to uncomment the following line:
+# want to uncomment the first line below.
+# Similarly for GNU SASL, unless pkg-config is used via AUTH_GSASL_PC.
+# Ditto for AUTH_HEIMDAL_GSSAPI(_PC).
# AUTH_LIBS=-lsasl2
+# AUTH_LIBS=-lgsasl
+# AUTH_LIBS=-lgssapi -lheimntlm -lkrb5 -lhx509 -lcom_err -lhcrypto -lasn1 -lwind -lroken -lcrypt
#------------------------------------------------------------------------------
# This setting is required for any TLS support (either OpenSSL or GnuTLS)
# SUPPORT_TLS=yes
-# Uncomment this setting if you are using OpenSSL
+# Uncomment one of these settings if you are using OpenSSL; pkg-config vs not
+# USE_OPENSSL_PC=openssl
# TLS_LIBS=-lssl -lcrypto
-# Uncomment these settings if you are using GnuTLS
+# Uncomment the first and either the second or the third of these if you
+# are using GnuTLS. If you have pkg-config, then the second, else the third.
# USE_GNUTLS=yes
+# USE_GNUTLS_PC=gnutls
# TLS_LIBS=-lgnutls -ltasn1 -lgcrypt
+# If using GnuTLS older than 2.10 and using pkg-config then note that Exim's
+# build process will require libgcrypt-config to exist in your $PATH. A
+# version that old is likely to become unsupported by Exim in 2017.
+
+# The security fix we provide with the gnutls_allow_auto_pkcs11 option
+# (4.82 PP/09) introduces a compatibility regression. The symbol is
+# not available if GnuTLS is build without p11-kit (--without-p11-kit
+# configure option). In this case use AVOID_GNUTLS_PKCS11=yes when
+# building Exim.
+# AVOID_GNUTLS_PKCS11=yes
+
# If you are running Exim as a server, note that just building it with TLS
# support is not all you need to do. You also need to set up a suitable
# certificate, and tell Exim about it by means of the tls_certificate
# if you are running Exim only as a client, building it with TLS support
# is all you need to do.
+# If you are using pkg-config then you should not need to worry where the
+# libraries and headers are installed, as the pkg-config .pc specification
+# should include all -L/-I information necessary. If not using pkg-config
+# then you might need to specify the locations too.
+
# Additional libraries and include files are required for both OpenSSL and
# GnuTLS. The TLS_LIBS settings above assume that the libraries are installed
# with all your other libraries. If they are in a special directory, you may
# with the extension "texinfo" in the doc directory. You may find that the
# version number of the texinfo files is different to your Exim version number,
# because the main documentation isn't updated as often as the code. For
-# example, if you have Exim version 4.43, the source tarball upacks into a
+# example, if you have Exim version 4.43, the source tarball unpacks into a
# directory called exim-4.43, but the texinfo tarball unpacks into exim-4.40.
# In this case, move the contents of exim-4.40/doc into exim-4.43/doc after you
# have unpacked them. Then set INFO_DIRECTORY to the location of your info
# If the exigrep utility is fed compressed log files, it tries to uncompress
# them using this command.
+# Leave it empty to enforce autodetection at runtime:
+# ZCAT_COMMAND=
+#
+# Omit the path if you want to use your system's PATH:
+# ZCAT_COMMAND=zcat
+#
+# Or specify the full pathname:
ZCAT_COMMAND=/usr/bin/zcat
-
#------------------------------------------------------------------------------
# Compiling in support for embedded Perl: If you want to be able to
# use Perl code in Exim's string manipulation language and you have Perl
# GNU/Linux -ldl is also needed.
+#------------------------------------------------------------------------------
+# Proxying.
+#
+# If you may want to use outbound (client-side) proxying, using Socks5,
+# uncomment the line below.
+
+# SUPPORT_SOCKS=yes
+
+# If you may want to use inbound (server-side) proxying, using Proxy Protocol,
+# uncomment the line below.
+
+# SUPPORT_PROXY=yes
+
+
+#------------------------------------------------------------------------------
+# Internationalisation.
+#
+# Uncomment the following to include Internationalisation features. This is the
+# SMTPUTF8 ESMTP extension, and associated facilities for handling UTF8 domain
+# and localparts, per RFC 3490 (IDNA2003).
+# You need to have the IDN library installed.
+# If you want IDNA2008 mappings per RFCs 5890, 6530 and 6533, you additionally
+# need libidn2 and SUPPORT_I18N_2008.
+
+# SUPPORT_I18N=yes
+# LDFLAGS += -lidn
+# SUPPORT_I18N_2008=yes
+# LDFLAGS += -lidn -lidn2
+
+
#------------------------------------------------------------------------------
# Support for authentication via Radius is also available. The Exim support,
# which is intended for use in conjunction with the SMTP AUTH facilities,
# There is no need to install all of SASL on your system. You just need to run
# ./configure --with-pwcheck, cd to the pwcheck directory within the sources,
# make and make install. You must create the socket directory (default
-# /var/pwcheck) and chown it to exim's user and group. Once you have installed
+# /var/pwcheck) and chown it to Exim's user and group. Once you have installed
# pwcheck, you should arrange for it to be started by root at boot time.
# CYRUS_PWCHECK_SOCKET=/var/pwcheck/pwcheck
#------------------------------------------------------------------------------
# Support for authentication via the Cyrus SASL saslauthd daemon is available.
-# The Exim support, which is intented for use in conjunction with the SMTP AUTH
+# The Exim support, which is intended for use in conjunction with the SMTP AUTH
# facilities, is included only when requested by setting the following
# parameter to the location of the saslauthd daemon's socket.
#
# ./configure --with-saslauthd (and any other options you need, for example, to
# select or deselect authentication mechanisms), cd to the saslauthd directory
# within the sources, make and make install. You must create the socket
-# directory (default /var/state/saslauthd) and chown it to exim's user and
+# directory (default /var/state/saslauthd) and chown it to Exim's user and
# group. Once you have installed saslauthd, you should arrange for it to be
# started by root at boot time.
#
# but of course there may need to be other things in CFLAGS and EXTRALIBS_EXIM
# as well.
+#
+# To use a name other than exim in the tcpwrappers config file,
+# e.g. if you're running multiple daemons with different access lists,
+# or multiple MTAs with the same access list, define
+# TCP_WRAPPERS_DAEMON_NAME accordingly
+#
+# TCP_WRAPPERS_DAEMON_NAME="exim"
#------------------------------------------------------------------------------
# USE_READLINE=yes
-# You may need to add -ldl to EXTRA_LIBS when you set USE_READLINE=yes.
+# You may need to add -ldl to EXTRALIBS when you set USE_READLINE=yes.
# Note that this option adds to the size of the Exim binary, because the
# dynamic loading library is not otherwise included.
+#------------------------------------------------------------------------------
+# Uncomment this setting to include IPv6 support.
+
+# HAVE_IPV6=yes
###############################################################################
# THINGS YOU ALMOST NEVER NEED TO MENTION #
# CHOWN_COMMAND=/usr/bin/chown
# CHGRP_COMMAND=/usr/bin/chgrp
+# CHMOD_COMMAND=/usr/bin/chmod
# MV_COMMAND=/bin/mv
# RM_COMMAND=/bin/rm
+# TOUCH_COMMAND=/usr/bin/touch
# PERL_COMMAND=/usr/bin/perl
# files, and thus be influenced by the value of TMPDIR. For this reason, when
# Exim starts, it checks the environment for TMPDIR, and if it finds it is set,
# it replaces the value with what is defined here. Commenting this setting
-# suppresses the check altogether.
+# suppresses the check altogether. Older installations call this macro
+# just TMPDIR, but this has side effects at build time. At runtime
+# TMPDIR is checked as before.
-TMPDIR="/tmp"
+EXIM_TMPDIR="/tmp"
#------------------------------------------------------------------------------
# to handle the different cases. If CONFIGURE_FILE_USE_EUID is defined, then
# Exim will first look for a configuration file whose name is that defined
# by CONFIGURE_FILE, with the effective uid tacked on the end, separated by
-# a period (for eximple, /usr/exim/configure.0). If this file does not exist,
+# a period (for example, /usr/exim/configure.0). If this file does not exist,
# then the bare configuration file name is tried. In the case when both
# CONFIGURE_FILE_USE_EUID and CONFIGURE_FILE_USE_NODE are set, four files
# are tried: <name>.<euid>.<node>, <name>.<node>, <name>.<euid>, and <name>.
# PERL_LIBS=
+#------------------------------------------------------------------------------
+# If you wish to disable valgrind in the binary, define NVALGRIND=1.
+# This should not be needed.
+
+# NVALGRIND=1
+
#------------------------------------------------------------------------------
# Identifying the daemon: When an Exim daemon starts up, it writes its pid
# (process id) to a file so that it can easily be identified. The path of the
# SUPPORT_MOVE_FROZEN_MESSAGES=yes
+
+#------------------------------------------------------------------------------
+# Expanding match_* second parameters: BE CAREFUL IF ENABLING THIS!
+# It has proven too easy in practice for administrators to configure security
+# problems into their Exim install, by treating match_domain{}{} and friends
+# as a form of string comparison, where the second string comes from untrusted
+# data. Because these options take lists, which can include lookup;LOOKUPDATA
+# style elements, a foe can then cause Exim to, eg, execute an arbitrary MySQL
+# query, dropping tables.
+# From Exim 4.77 onwards, the second parameter is not expanded; it can still
+# be a list literal, or a macro, or a named list reference. There is also
+# the new expansion condition "inlisti" which does expand the second parameter,
+# but treats it as a list of strings; also, there's "eqi" which is probably
+# what is normally wanted.
+#
+# If you really need to have the old behaviour, know what you are doing and
+# will not complain if your system is compromised as a result of doing so, then
+# uncomment this option to get the old behaviour back.
+
+# EXPAND_LISTMATCH_RHS=yes
+
+#------------------------------------------------------------------------------
+# Disabling the use of fsync(): DO NOT UNCOMMENT THE FOLLOWING LINE unless you
+# really, really, really know what you are doing. And even then, think again.
+# You should never uncomment this when compiling a binary for distribution.
+# Use it only when compiling Exim for your own use.
+#
+# Uncommenting this line enables the use of a runtime option called
+# disable_fsync, which can be used to stop Exim using fsync() to ensure that
+# files are written to disc before proceeding. When this is disabled, crashes
+# and hardware problems such as power outages can cause data to be lost. This
+# feature should only be used in very exceptional circumstances. YOU HAVE BEEN
+# WARNED.
+
+# ENABLE_DISABLE_FSYNC=yes
+
# End of EDITME for Exim 4.