[exim.git] / doc / doc-txt / IncompatibleChanges
1 Preamble
2 ========
4 Normally The Exim Maintainers ensure that a configuration which works
5 with version N will work with version N+1, within a major version number
6 (eg, 4).
8 Occasionally this will not be the case; usually, those changes will be
9 at the end of a long notice period where admins have been encouraged to
10 move away and even then, we are hesitant to fully break things without
11 strong cause to move away.
13 This does not apply to "experimental" features, which can be withdrawn
14 or changed with little notice, although we still endeavour to limit
15 that. We may choose to note those changes here too.
17 The most likely cause of a backwards-incompatible change is a security
18 improvement, where the benefits for everyone strongly outweigh the needs
19 of the few.
22 Changes
23 =======
25 Exim version 4.73
26 -----------------
28 * The Exim run-time user can no longer be root; this was always
29 strongly discouraged, but is now prohibited both at build and
30 run-time. If you need Exim to run routinely as root, you'll need to
31 patch the source and accept the risk. Here be dragons.
33 * Exim will no longer accept a configuration file owned by the Exim
34 run-time user, unless that account is explicitly the value in
35 CONFIGURE_OWNER, which we discourage. Exim now checks to ensure that
36 files are not writable by other accounts.
38 * The ALT_CONFIG_ROOT_ONLY build option is no longer optional and is forced
39 on; the Exim user can, by default, no longer use -C/-D and retain privilege.
40 Two new build options mitigate this.
42 * TRUSTED_CONFIG_LIST defines a file containing a whitelist of config
43 files that are trusted to be selected by the Exim user; one per line.
44 This is the recommended approach going forward.
46 * WHITELIST_D_MACROS defines a colon-separated list of macro names which
47 the Exim run-time user may safely pass without dropping privileges.
48 Because changes to this involve a recompile, this is not the recommended
49 approach but may ease transition. The values of the macros, when
50 overriden, are constrained to match this regex: ^[A-Za-z0-9_/.-]*$
52 * The system_filter_user option now defaults to the Exim run-time user,
53 rather than root. You can still set it explicitly to root and this
54 can be done with prior versions too, letting you roll versions
55 without needing to change this configuration option.
57 * ClamAV must be at least version 0.95 unless WITH_OLD_CLAMAV_STREAM is
58 defined at build time.