# HG changeset patch
# User Ben Schmidt
# Date 1289776288 -39600
# Node ID ddae562f7cf0359e357ea83a10ef3bb20b16de49
# Parent  93d445688ebe702186d14ee25627ed50200220f7
Document why 'nobody' is inappropriate and capitalise a few things

diff -r 93d445688ebe -r ddae562f7cf0 README.postfix
--- a/README.postfix	Mon Nov 15 09:36:38 2010 +1100
+++ b/README.postfix	Mon Nov 15 10:11:28 2010 +1100
@@ -2,8 +2,8 @@
 
 POSTFIX ISSUES
    
-    The main issue with Postfix and mlmmj is the mlmmj requirement that
-    the mlmmj executables must be executed by root or the owner of the
+    The main issue with Postfix and Mlmmj is the Mlmmj requirement that
+    the Mlmmj executables must be executed by root or the owner of the
     list directory.  
 
     This is at odds with Postfix.  The standard local delivery mechanism
@@ -19,12 +19,24 @@
     files are disabled as a security precaution in aliases files for
     delivering to external programs.
 
-    This leaves us with a conundrum on how to execute the mlmmj
-    executables as an 'mlmmj' user without using alias files.  One
-    answer is to use a postfix transport.
+    So Postfix then falls back to executing with the user specified by
+    the configuration option 'default_privs'.  The default setting for
+    this option is the user 'nobody'.  You can make Mlmmj work by having
+    your lists owned by 'nobody', but this is not recommended.  Other
+    programs and daemons may use 'nobody' as a user who should not have
+    access to anything; most notably, some NFS implementations use this
+    user when somebody connects but fails to authenticate.  Such users
+    should not be able to access your mailing lists.  Changing
+    'default_privs' to an 'mlmmj' user may open other security holes,
+    and may not be appropriate if Postfix is used for other external
+    programs besides Mlmmj.
+
+    This leaves us with a conundrum on how to execute the Mlmmj
+    executables as an 'mlmmj' user.  One answer is to use a Postfix
+    transport.
 
     First we'll get the 'mlmmj' user setup and then move onto the
-    postfix configuration:
+    Postfix configuration:
 
 MLMMJ SETUP
     
@@ -51,8 +63,8 @@
 
     Add a virtual_alias_map file to main.cf configuration.  We'll use a
     regular expression map since we need to be able to match all the
-    various mjmml delimiter addresses (list-subscribe, list-unsubscribe,
-    etc)
+    various Mlmmj delimiter addresses (list-subscribe, list-unsubscribe,
+    confsub-0123456789abcdef, etc.).
 
         main.cf:
             virtual_alias_maps = hash:/etc/postfix/virtual, 
@@ -72,7 +84,7 @@
 
         /^(list-name.*)@(domain\.com)$/        domain--${1}
 
-    Next we make sure that postfix can invoke the mlmmj executables as
+    Next we make sure that Postfix can invoke the mlmmj executables as
     the 'mlmmj' user.  This is where the transport map comes in.  So we
     add a transport map and a configuration option that instructs the
     transport to only deliver one file at a time.  See transport(5) for
@@ -97,7 +109,7 @@
         /^(domain--list-name).*$/              mlmmj:domain/list-name
 
     Now we setup the 'mlmmj' transport.  The 'mlmmj' in mlmmj:$1 above
-    indicates a transport listed in the postfix master.cf file.  We are
+    indicates a transport listed in the Postfix master.cf file.  We are
     just going to create a transport called 'mlmmj' but it is nothing
     more than a pipe(8) to the mlmmj-receive program that is invoked as
     the 'mlmmj' user.
@@ -107,7 +119,7 @@
             mlmmj   unix  -       n       n       -       -       pipe
                 flags=DORhu user=mlmmj argv=/usr/local/bin/mlmmj-receive -F -L /var/spool/mlmmj/$nexthop/
 
-    This takes the pipe(8) postfix delivery agent and tells it to invoke
+    This takes the pipe(8) Postfix delivery agent and tells it to invoke
     '/usr/local/bin/mlmmj-receive' as the 'mlmmj' user and pipe the
     email to it on stdin.  This mode of transportation is given the name
     'mlmmj'.
@@ -129,6 +141,6 @@
     /var/spool/mlmmj/list-name as usual, or for the hierarchical
     multi-domain version, in /var/spool/mlmmj/domain/list-name.
 
-    Restart postfix and enjoy your new lists.
+    Restart Postfix and enjoy your new lists.