Mailscanner + Exim >= 4.73

[George B.]

Hello,

This is really an Exim question so feel free to tell me to ask 
elsewhere... ;-) It is related to my MailScanner configuration though.

Apparently Exim 4.73 will not allow any "-D" options by default and 
eventually the functionality will be removed. From mailing list post:

http://lists.exim.org/lurker/message/20101215.161702.fcdb3f77.gl.html
---
+# 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_PREFIX_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 overriden 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.
---

I think I am already seeing symptoms of this on my Debian Squeeze box 
which relies (as per documentation of the rather old Debian MailScanner 
package) on the "-DOUTGING" option for the split pool configuration:
---
scruffy:~# exim4 -bP -DOUTGOING spool_directory
macros_trusted overriden to true by whitelisting
spool_directory = /var/spool/exim4

vs

scruffy:~# exim4 -bP spool_directory
spool_directory = /var/spool/exim4_incoming
---

I have only just noticed this an I am looking for some advice on how to 
"future-proof" my Mailscanner + Exim4 implementation.

The message above talks about a "shim configuration file" but I don't 
really understand what they are talking about there and how to use it 
for split pool configuration. :-(

Any pointers would be greatly appreciated.


Thanks,

George.