3 ### Spam filtering for distorted.org.uk Exim configuration
5 ### (c) 2012 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
10 ### This program is free software; you can redistribute it and/or modify
11 ### it under the terms of the GNU General Public License as published by
12 ### the Free Software Foundation; either version 2 of the License, or
13 ### (at your option) any later version.
15 ### This program is distributed in the hope that it will be useful,
16 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 ### GNU General Public License for more details.
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22 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
25 ###--------------------------------------------------------------------------
28 ## The Exim documentation tells lies.
30 ## : *${run{*<_command_>* *<_args_>*}{*<_string1_>*}{*<_string2_>*}}*
31 ## : The command and its arguments are first expanded separately, [...]
33 ## They aren't. The whole command-and-args are expanded together, and then
34 ## split at unquoted spaces. This unpleasant hack sorts out the mess.
35 m4_define(<:SHQUOTE:>, <:"${rxquote:$1}":>)
37 SECTION(global, policy)m4_dnl
38 spamd_address = CONF_spamd_address CONF_spamd_port
40 SECTION(routers, allspam)m4_dnl
41 ## If we're verifying an address and the recipient has a `~/.mail/spam-limit'
42 ## file, then look up the recipient and sender addresses to find a plausible
43 ## limit and insert it into the `address_data' where the RCPT ACL can find
44 ## it. This router always declines, so it doesn't affect the overall outcome
45 ## of the verification.
50 local_part_suffix = CONF_user_suffix_list
51 local_part_suffix_optional = true
54 ${if def:address_data {$address_data}{}} \
55 ${if and {{!eq{$acl_c_mode}{submission}} \
56 {exists {CONF_userconf_dir/spam-limit}}} \
57 {${lookup {$local_part_prefix\
62 nwildlsearch {CONF_userconf_dir/spam-limit} \
63 {${if match{$value}{\N^-?[0-9]+$\N} \
68 ${if and {{!eq{$acl_c_mode}{submission}} \
69 {exists {CONF_userconf_dir/spam-limit.userv}}} \
70 {${run {/usr/bin/timeout 5s -- \
71 userv CONF_userv_opts SHQUOTE($local_part) exim-spam-limit \
72 SHQUOTE($sender_address) \
73 SHQUOTE($local_part_prefix) \
74 SHQUOTE($local_part) \
75 SHQUOTE($local_part_suffix) \
77 {${if match{$value}{\N^-?[0-9]+$\N} \
83 SECTION(acl, rcpt-hooks)m4_dnl
84 ## Do per-recipient spam-filter processing.
85 require acl = rcpt_spam
87 SECTION(acl, misc)m4_dnl
90 ## If the client is trusted, or this is a new submission, don't
91 ## bother with any of this. We will have verified the sender
92 ## fairly aggressively before granting this level of trust.
93 accept hosts = +trusted
94 accept condition = ${if eq{$acl_c_mode}{submission}}
96 ## Otherwise we should check.
101 ## See if we should do this check.
102 accept acl = skip_spam_check
104 ## Always accept mail to `postmaster'. Currently this is not
105 ## negotiable; maybe a tweak can be added to `domains.conf' if
107 accept local_parts = postmaster
109 ## Collect the user's spam threshold from the `address_data'
110 ## variable, where it was left by the `fetch_spam_limit' router
111 ## during recipient verification. (This just saves duplicating this
112 ## enormous expression.)
113 warn set acl_m_this_spam_limit = \
114 ${sg {${extract {spam_limit} \
115 {${if def:address_data \
116 {$address_data}{}}} \
118 {^(|.*\\D.*)\$}{CONF_spam_max}}
120 ## If there's a spam limit already established, and it's different
121 ## from this user's limit, then the sender will have to try this user
123 defer !hosts = +trusted
124 message = "You'd better try this one later"
125 condition = ${if def:acl_m_spam_limit {true}{false}}
126 condition = ${if ={$acl_m_spam_limit} \
127 {$acl_m_this_spam_limit} \
130 ## There's no limit set yet, or the user's limit is the same as the
131 ## existing one, or the client's local and we're not checking for
132 ## spam anyway. Whichever way, it's safe to set it now.
133 warn set acl_m_spam_limit = $acl_m_this_spam_limit
138 SECTION(acl, data-spam)m4_dnl
140 require acl = data_spam
142 SECTION(acl, misc)m4_dnl
145 ## See if we should do this check.
146 accept acl = skip_spam_check
148 ## Check header validity.
149 require verify = header_syntax
151 ## Check the message for spam, comparing to the configured limit.
152 deny spam = exim:true
153 message = Tinned meat product detected ($spam_score)
154 condition = ${if >{$spam_score_int}{$acl_m_spam_limit} \
157 ## Insert headers from the spam check now that we've decided to
158 ## accept the message.
161 ## Convert the limit (currently 10x fixed point) into a
162 ## decimal for presentation.
163 set acl_m_spam_limit_presentation = \
164 ${sg{$acl_m_spam_limit}{\N(\d)$\N}{.\$1}}
166 ## Convert the report into something less obnoxious. Plain
167 ## old SpamAssassin has an `X-Spam-Status' header which
168 ## lists the matched rules and provides some other basic
169 ## information. Try to extract something similar from the
172 ## This is rather fiddly.
174 ## Firstly, escape angle brackets, because we'll be using
175 ## them for our own purposes.
176 set acl_m_spam_tests = ${sg{$spam_report}{([!<>])}{!\$1}}
178 ## Trim off the blurb paragraph and the preview. The rest
179 ## should be fairly well behaved. Wrap double angle-
180 ## brackets around the remainder; these can't appear in the
181 ## body because we escaped them all earlier.
182 set acl_m_spam_tests = \
183 ${sg{$acl_m_spam_tests} \
184 {\N^(?s).*\n Content analysis details:(.*)$\N} \
187 ## Extract the information about the matching rules and
188 ## their scores. Leave `<<...>>' around everything else.
189 set acl_m_spam_tests = \
190 ${sg{$acl_m_spam_tests} \
191 {\N(?s)\n\s*(-?[\d.]+)\s+([-\w]+)\s\N} \
194 ## Strip everything still in `<<...>>' pairs, including any
195 ## escaped characters inside.
196 set acl_m_spam_tests = \
197 ${sg{$acl_m_spam_tests}{\N(?s)<<([^!>]+|!.)*>>\N}{}}
199 ## Trim off a trailing comma.
200 set acl_m_spam_tests = ${sg{$acl_m_spam_tests}{,\s*\$}{}}
202 ## Undo the escaping.
203 set acl_m_spam_tests = ${sg{$acl_m_spam_tests}{!(.)}{\$1}}
205 ## Insert the headers.
206 add_header = X-SpamAssassin-Score: \
207 $spam_score/$acl_m_spam_limit_presentation \
209 add_header = X-SpamAssassin-Status: \
211 limit=$acl_m_spam_limit_presentation, \n\t\
212 tests=$acl_m_spam_tests
218 ###----- That's all, folks --------------------------------------------------