rspamd/rules/regexp/headers.lua

-- Actually these regular expressions were obtained from SpamAssassin project, so they are licensed by apache license:
--
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements.  See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to you under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License.  You may obtain a copy of the License at:
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Definitions of header regexps

local reconf = config['regexp']

-- Subject needs encoding
-- Define encodings types
local subject_encoded_b64 = 'Subject=/=\\?\\S+\\?B\\?/iX'
local subject_encoded_qp = 'Subject=/=\\?\\S+\\?Q\\?/iX'
-- Define whether subject must be encoded (contains non-7bit characters)
local subject_needs_mime = 'Subject=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/X'
-- Final rule
reconf['SUBJECT_NEEDS_ENCODING'] = {
  re = string.format('!(%s) & !(%s) & (%s)', subject_encoded_b64, subject_encoded_qp, subject_needs_mime),
  score = 1.0,
  mime_only = true,
  description = 'Subject needs encoding',
  group = 'headers'
}

local from_encoded_b64 = 'From=/=\\?\\S+\\?B\\?/iX'
local from_encoded_qp = 'From=/=\\?\\S+\\?Q\\?/iX'
local raw_from_needs_mime = 'From=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/X'
reconf['FROM_NEEDS_ENCODING'] = {
  re = string.format('!(%s) & !(%s) & (%s)', from_encoded_b64, from_encoded_qp, raw_from_needs_mime),
  score = 1.0,
  mime_only = true,
  description = 'From header needs encoding',
  group = 'headers'
}

local to_encoded_b64 = 'To=/=\\?\\S+\\?B\\?/iX'
local to_encoded_qp = 'To=/=\\?\\S+\\?Q\\?/iX'
local raw_to_needs_mime = 'To=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/X'
reconf['TO_NEEDS_ENCODING'] = {
  re = string.format('!(%s) & !(%s) & (%s)', to_encoded_b64, to_encoded_qp, raw_to_needs_mime),
  score = 1.0,
  mime_only = true,
  description = 'To header needs encoding',
  group = 'headers'
}

-- Detects that there is no space in From header (e.g. Some Name<some@host>)
reconf['R_NO_SPACE_IN_FROM'] = {
  re = 'From=/\\S<[-\\w\\.]+\\@[-\\w\\.]+>/X',
  score = 1.0,
  mime_only = true,
  description = 'No space in from header',
  group = 'headers'
}

reconf['TO_WRAPPED_IN_SPACES'] = {
  re = [[To=/<\s[-.\w]+\@[-.\w]+\s>/X]],
  score = 2.0,
  mime_only = true,
  description = 'To address is wrapped in spaces inside angle brackets (e.g. display-name < local-part@domain >)',
  group = 'headers'
}

-- Detects missing Subject header
reconf['MISSING_SUBJECT'] = {
  re = '!raw_header_exists(Subject)',
  score = 2.0,
  mime_only = true,
  description = 'Subject header is missing',
  group = 'headers'
}

rspamd_config.EMPTY_SUBJECT = {
  score = 1.0,
  mime_only = true,
  description = 'Subject header is empty',
  group = 'headers',
  callback = function(task)
    local hdr = task:get_header('Subject')
    if hdr and #hdr == 0 then
      return true
    end
    return false
  end
}

-- Detects missing To header
reconf['MISSING_TO'] = {
  re = '!raw_header_exists(To)',
  score = 2.0,
  description = 'To header is missing',
  group = 'headers',
  mime_only = true,
}

-- Detects undisclosed recipients
reconf['R_UNDISC_RCPT'] = {
  -- match:
  -- To: undisclosed-recipients:;
  -- To: Undisclosed recipients:;
  -- To: undisclosed-recipients: ;
  -- To: <Undisclosed-Recipient:;>
  -- To: "undisclosed-recipients (utajeni adresati)": ;
  -- To: Undisclosed recipients:
  -- but do not match:
  -- Undisclosed Recipient <user@example.org>
  re = [[To=/^[<"]?undisclosed[- ]recipients?\b.*:/i{header}]],
  score = 3.0,
  description = 'Recipients are absent or undisclosed',
  group = 'headers',
  mime_only = true,
}

-- Detects missing Message-Id
local has_mid = 'header_exists(Message-Id)'
reconf['MISSING_MID'] = {
  re = '!header_exists(Message-Id)',
  score = 2.5,
  description = 'Message id is missing',
  group = 'headers',
  mime_only = true,
}

-- Received seems to be fake
reconf['R_RCVD_SPAMBOTS'] = {
  re = 'Received=/^from \\[\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\] by [-.\\w+]{5,255}; [SMTWF][a-z][a-z],' ..
      ' [\\s\\d]?\\d [JFMAJSOND][a-z][a-z] \\d{4} \\d{2}:\\d{2}:\\d{2} [-+]\\d{4}$/mH',
  score = 3.0,
  description = 'Spambots signatures in received headers',
  group = 'headers',
  mime_only = true,
}

-- Charset is missing in message
reconf['R_MISSING_CHARSET'] = {
  re = string.format('!is_empty_body() & content_type_is_type(text) & content_type_is_subtype(plain) & !content_type_has_param(charset) & !%s',
      'compare_transfer_encoding(7bit)'),
  score = 0.5,
  description = 'Charset is missing in a message',
  group = 'headers',
  mime_only = true,
}

-- Find forged Outlook MUA
-- Yahoo groups messages
local yahoo_bulk = 'Received=/from \\[\\S+\\] by \\S+\\.(?:groups|scd|dcn)\\.yahoo\\.com with NNFMP/H'
-- Outlook MUA
local outlook_mua = 'X-Mailer=/^Microsoft Outlook\\b/H'
local any_outlook_mua = 'X-Mailer=/^Microsoft Outlook\\b/H'
reconf['FORGED_OUTLOOK_HTML'] = {
  re = string.format('!%s & %s & %s', yahoo_bulk, outlook_mua, 'has_only_html_part()'),
  score = 5.0,
  description = 'Forged outlook HTML signature',
  group = 'headers',
  mime_only = true,
}

-- Recipients seems to be likely with each other (only works when recipients count is more than 5 recipients)
reconf['SUSPICIOUS_RECIPS'] = {
  re = 'compare_recipients_distance(0.65)',
  score = 1.5,
  description = 'Recipients seems to be autogenerated (works if recipients count is more than 5)',
  group = 'headers',
  mime_only = true,
}

-- Recipients list seems to be sorted
reconf['SORTED_RECIPS'] = {
  re = 'is_recipients_sorted()',
  score = 3.5,
  description = 'Recipients list seems to be sorted',
  group = 'headers',
  mime_only = true,
}

-- Spam string at the end of message to make statistics faults
reconf['TRACKER_ID'] = {
  re = '/^[a-z0-9]{6,24}[-_a-z0-9]{12,36}[a-z0-9]{6,24}\\s*\\z/isPr',
  score = 3.84,
  description = 'Spam string at the end of message to make statistics fault',
  group = 'headers',
  mime_only = true,
}

-- From contains only 7bit characters (parsed headers are used)
local from_needs_mime = 'From=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/Hr'
-- From that contains encoded characters while base 64 is not needed as all symbols are 7bit
reconf['FROM_EXCESS_BASE64'] = {
  re = string.format('%s & !%s', from_encoded_b64, from_needs_mime),
  score = 1.5,
  description = 'From that contains encoded characters while base 64 is not needed as all symbols are 7bit',
  group = 'excessb64',
  mime_only = true,
}

-- From that contains encoded characters while quoted-printable is not needed as all symbols are 7bit
reconf['FROM_EXCESS_QP'] = {
  re = string.format('%s & !%s', from_encoded_qp, from_needs_mime),
  score = 1.2,
  description = 'From that contains encoded characters while quoted-printable is not needed as all symbols are 7bit',
  group = 'excessqp'
}

-- To contains only 7bit characters (parsed headers are used)
local to_needs_mime = 'To=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/Hr'
-- To that contains encoded characters while base 64 is not needed as all symbols are 7bit
reconf['TO_EXCESS_BASE64'] = {
  re = string.format('%s & !%s', to_encoded_b64, to_needs_mime),
  score = 1.5,
  description = 'To that contains encoded characters while base 64 is not needed as all symbols are 7bit',
  group = 'excessb64'
}

-- To that contains encoded characters while quoted-printable is not needed as all symbols are 7bit
-- Final rule
reconf['TO_EXCESS_QP'] = {
  re = string.format('%s & !%s', to_encoded_qp, to_needs_mime),
  score = 1.2,
  description = 'To that contains encoded characters while quoted-printable is not needed as all symbols are 7bit',
  group = 'excessqp'
}

-- Reply-To that contains encoded characters while base 64 is not needed as all symbols are 7bit
-- Regexp that checks that Reply-To header is encoded with base64 (search in raw headers)
local replyto_encoded_b64 = 'Reply-To=/\\=\\?\\S+\\?B\\?/iX'
-- Reply-To contains only 7bit characters (parsed headers are used)
local replyto_needs_mime = 'Reply-To=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/Hr'
-- Final rule
reconf['REPLYTO_EXCESS_BASE64'] = {
  re = string.format('%s & !%s', replyto_encoded_b64, replyto_needs_mime),
  score = 1.5,
  description = 'Reply-To that contains encoded characters while base 64 is not needed as all symbols are 7bit',
  group = 'excessb64'
}

-- Reply-To that contains encoded characters while quoted-printable is not needed as all symbols are 7bit
-- Regexp that checks that Reply-To header is encoded with quoted-printable (search in raw headers)
local replyto_encoded_qp = 'Reply-To=/\\=\\?\\S+\\?Q\\?/iX'
-- Final rule
reconf['REPLYTO_EXCESS_QP'] = {
  re = string.format('%s & !%s', replyto_encoded_qp, replyto_needs_mime),
  score = 1.2,
  description = 'Reply-To that contains encoded characters while quoted-printable is not needed as all symbols are 7bit',
  group = 'excessqp'
}

-- Cc that contains encoded characters while base 64 is not needed as all symbols are 7bit
-- Regexp that checks that Cc header is encoded with base64 (search in raw headers)
local cc_encoded_b64 = 'Cc=/\\=\\?\\S+\\?B\\?/iX'
-- Co contains only 7bit characters (parsed headers are used)
local cc_needs_mime = 'Cc=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/Hr'
-- Final rule
reconf['CC_EXCESS_BASE64'] = {
  re = string.format('%s & !%s', cc_encoded_b64, cc_needs_mime),
  score = 1.5,
  description = 'Cc that contains encoded characters while base 64 is not needed as all symbols are 7bit',
  group = 'excessb64'
}

-- Cc that contains encoded characters while quoted-printable is not needed as all symbols are 7bit
-- Regexp that checks that Cc header is encoded with quoted-printable (search in raw headers)
local cc_encoded_qp = 'Cc=/\\=\\?\\S+\\?Q\\?/iX'
-- Final rule
reconf['CC_EXCESS_QP'] = {
  re = string.format('%s & !%s', cc_encoded_qp, cc_needs_mime),
  score = 1.2,
  description = 'Cc that contains encoded characters while quoted-printable is not needed as all symbols are 7bit',
  group = 'excessqp'
}

local subj_encoded_b64 = 'Subject=/\\=\\?\\S+\\?B\\?/iX'
local subj_needs_mime = 'Subject=/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f-\\xff]/Hr'
reconf['SUBJ_EXCESS_BASE64'] = {
  re = string.format('%s & !%s', subj_encoded_b64, subj_needs_mime),
  score = 1.5,
  description = 'Subject is unnecessarily encoded in base64',
  group = 'excessb64'
}

local subj_encoded_qp = 'Subject=/\\=\\?\\S+\\?Q\\?/iX'
reconf['SUBJ_EXCESS_QP'] = {
  re = string.format('%s & !%s', subj_encoded_qp, subj_needs_mime),
  score = 1.2,
  description = 'Subject is unnecessarily encoded in quoted-printable',
  group = 'excessqp'
}

-- Detect forged outlook headers
-- OE X-Mailer header
local oe_mua = 'X-Mailer=/\\bOutlook Express [456]\\./H'
-- OE Message ID format
local oe_msgid_1 = 'Message-Id=/^<?[A-Za-z0-9-]{7}[A-Za-z0-9]{20}\\@hotmail\\.com>?$/mH'
local oe_msgid_2 = 'Message-Id=/^<?(?:[0-9a-f]{8}|[0-9a-f]{12})\\$[0-9a-f]{8}\\$[0-9a-f]{8}\\@\\S+>?$/H'
-- EZLM remail of message
local lyris_ezml_remailer = 'List-Unsubscribe=/<mailto:(?:leave-\\S+|\\S+-unsubscribe)\\@\\S+>$/H'
-- Header of wacky sendmail
local wacky_sendmail_version = 'Received=/\\/CWT\\/DCE\\)/H'
-- Iplanet received header
local iplanet_messaging_server = 'Received=/iPlanet Messaging Server/H'
-- Hotmail message id
local hotmail_baydav_msgid = 'Message-Id=/^<?BAY\\d+-DAV\\d+[A-Z0-9]{25}\\@phx\\.gbl?>$/H'
-- Sympatico message id
local sympatico_msgid = 'Message-Id=/^<?BAYC\\d+-PASMTP\\d+[A-Z0-9]{25}\\@CEZ\\.ICE>?$/H'
-- Mailman message id
-- https://bazaar.launchpad.net/~mailman-coders/mailman/2.1/view/head:/Mailman/Utils.py#L811
local mailman_msgid = [[Message-ID=/^<mailman\.\d+\.\d+\.\d+\.[-+.:=\w]+@[-a-zA-Z\d.]+>$/H]]
-- Message id seems to be forged
local unusable_msgid = string.format('(%s | %s | %s | %s | %s | %s)',
    lyris_ezml_remailer, wacky_sendmail_version,
    iplanet_messaging_server, hotmail_baydav_msgid, sympatico_msgid, mailman_msgid)
-- Outlook express data seems to be forged
local forged_oe = string.format('(%s & !%s & !%s & !%s)', oe_mua, oe_msgid_1, oe_msgid_2, unusable_msgid)
-- Outlook specific headers
local outlook_dollars_mua = 'X-Mailer=/^Microsoft Outlook(?: 8| CWS, Build 9|, Build 10)\\./H'
local outlook_dollars_other = 'Message-Id=/^<?\\!\\~\\!>?/H'
local vista_msgid = 'Message-Id=/^<?[A-F\\d]{32}\\@\\S+>?$/H'
local ims_msgid = 'Message-Id=/^<?[A-F\\d]{36,40}\\@\\S+>?$/H'
-- Forged outlook headers
local forged_outlook_dollars = string.format('(%s & !%s & !%s & !%s & !%s & !%s)',
    outlook_dollars_mua, oe_msgid_2, outlook_dollars_other, vista_msgid, ims_msgid, unusable_msgid)
-- Outlook versions that should be excluded from summary rule
local fmo_excl_o3416 = 'X-Mailer=/^Microsoft Outlook, Build 10.0.3416$/H'
local fmo_excl_oe3790 = 'X-Mailer=/^Microsoft Outlook Express 6.00.3790.3959$/H'
-- Summary rule for forged outlook
reconf['FORGED_MUA_OUTLOOK'] = {
  re = string.format('(%s | %s) & !%s & !%s & !%s',
      forged_oe, forged_outlook_dollars, fmo_excl_o3416, fmo_excl_oe3790, vista_msgid),
  score = 3.0,
  description = 'Forged outlook MUA',
  group = 'mua'
}

-- HTML outlook signs
local mime_html = 'content_type_is_type(text) & content_type_is_subtype(/.?html/)'
local tag_exists_html = 'has_html_tag(html)'
local tag_exists_head = 'has_html_tag(head)'
local tag_exists_meta = 'has_html_tag(meta)'
local tag_exists_body = 'has_html_tag(body)'
reconf['FORGED_OUTLOOK_TAGS'] = {
  re = string.format('!%s & %s & %s & !(%s & %s & %s & %s)',
      yahoo_bulk, any_outlook_mua, mime_html, tag_exists_html, tag_exists_head,
      tag_exists_meta, tag_exists_body),
  score = 2.1,
  description = "Message pretends to be send from Outlook but has 'strange' tags",
  group = 'headers'
}

-- Forged OE/MSO boundary
reconf['SUSPICIOUS_BOUNDARY'] = {
  re = 'Content-Type=/^\\s*multipart.+boundary="----=_NextPart_000_[A-Z\\d]{4}_(00EBFFA4|0102FFA4|32C6FFA4|3302FFA4)\\.[A-Z\\d]{8}"[\\r\\n]*$/siX',
  score = 5.0,
  description = 'Suspicious boundary in header Content-Type',
  group = 'mua'
}
-- Forged OE/MSO boundary
reconf['SUSPICIOUS_BOUNDARY2'] = {
  re = 'Content-Type=/^\\s*multipart.+boundary="----=_NextPart_000_[A-Z\\d]{4}_(01C6527E)\\.[A-Z\\d]{8}"[\\r\\n]*$/siX',
  score = 4.0,
  description = 'Suspicious boundary in header Content-Type',
  group = 'mua'
}
-- Forged OE/MSO boundary
reconf['SUSPICIOUS_BOUNDARY3'] = {
  re = 'Content-Type=/^\\s*multipart.+boundary="-----000-00\\d\\d-01C[\\dA-F]{5}-[\\dA-F]{8}"[\\r\\n]*$/siX',
  score = 3.0,
  description = 'Suspicious boundary in header Content-Type',
  group = 'mua'
}
-- Forged OE/MSO boundary
local suspicious_boundary_01C4	= 'Content-Type=/^\\s*multipart.+boundary="----=_NextPart_000_[A-Z\\d]{4}_01C4[\\dA-F]{4}\\.[A-Z\\d]{8}"[\\r\\n]*$/siX'
local suspicious_boundary_01C4_date	= 'Date=/^\\s*\\w\\w\\w,\\s+\\d+\\s+\\w\\w\\w 20(0[56789]|1\\d)/'
reconf['SUSPICIOUS_BOUNDARY4'] = {
  re = string.format('(%s) & (%s)', suspicious_boundary_01C4, suspicious_boundary_01C4_date),
  score = 4.0,
  description = 'Suspicious boundary in header Content-Type',
  group = 'mua'
}

-- Detect forged The Bat! headers
-- The Bat! X-Mailer header
local thebat_mua_any = 'X-Mailer=/^\\s*The Bat!/H'
-- The Bat! common Message-ID template
local thebat_msgid_common = 'Message-ID=/^<?\\d+\\.\\d+\\@\\S+>?$/mH'
-- Correct The Bat! Message-ID template
local thebat_msgid = 'Message-ID=/^<?\\d+\\.(19[789]\\d|20\\d\\d)(0\\d|1[012])([012]\\d|3[01])([0-5]\\d)([0-5]\\d)([0-5]\\d)\\@\\S+>?/mH'
-- Summary rule for forged The Bat! Message-ID header
reconf['FORGED_MUA_THEBAT_MSGID'] = {
  re = string.format('(%s) & !(%s) & (%s) & !(%s)', thebat_mua_any, thebat_msgid, thebat_msgid_common, unusable_msgid),
  score = 4.0,
  description = 'Message pretends to be send from The Bat! but has forged Message-ID',
  group = 'mua'
}
-- Summary rule for forged The Bat! Message-ID header with unknown template
reconf['FORGED_MUA_THEBAT_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !(%s) & !(%s) & !(%s)', thebat_mua_any, thebat_msgid, thebat_msgid_common, unusable_msgid),
  score = 3.0,
  description = 'Message pretends to be send from The Bat! but has forged Message-ID',
  group = 'mua'
}

-- Detect forged KMail headers
-- KMail User-Agent header
local kmail_mua = 'User-Agent=/^\\s*KMail\\/1\\.\\d+\\.\\d+/H'
-- KMail common Message-ID template
local kmail_msgid_common = 'Message-Id=/^<?\\s*\\d+\\.\\d+\\.\\S+\\@\\S+>?$/mH'
-- Summary rule for forged KMail Message-ID header with unknown template
reconf['FORGED_MUA_KMAIL_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !(%s) & !(%s)', kmail_mua, kmail_msgid_common, unusable_msgid),
  score = 2.5,
  description = 'Message pretends to be send from KMail but has forged Message-ID',
  group = 'mua'
}

-- Detect forged Opera Mail headers
-- Opera Mail User-Agent header
local opera1x_mua = 'User-Agent=/^\\s*Opera Mail\\/1[01]\\.\\d+ /H'
-- Opera Mail Message-ID template
local opera1x_msgid = 'Message-ID=/^<?op\\.[a-z\\d]{14}\\@\\S+>?$/H'
-- Rule for forged Opera Mail Message-ID header
reconf['FORGED_MUA_OPERA_MSGID'] = {
  re = string.format('(%s) & !(%s) & !(%s)', opera1x_mua, opera1x_msgid, unusable_msgid),
  score = 4.0,
  description = 'Message pretends to be send from Opera Mail but has forged Message-ID',
  group = 'mua'
}

-- Detect forged Mozilla Mail/Thunderbird/Seamonkey/Postbox headers
-- Mozilla based X-Mailer
local user_agent_mozilla5	= 'User-Agent=/^\\s*Mozilla\\/5\\.0/H'
local user_agent_thunderbird	= 'User-Agent=/^\\s*(Thunderbird|Mozilla Thunderbird|Mozilla\\/.*Gecko\\/.*(Thunderbird|Icedove)\\/)/H'
local user_agent_seamonkey	= 'User-Agent=/^\\s*Mozilla\\/5\\.0\\s.+\\sSeaMonkey\\/\\d+\\.\\d+/H'
local user_agent_postbox	= [[User-Agent=/^\s*Mozilla\/5\.0\s\([^)]+\)\sGecko\/\d+\sPostboxApp\/\d+(?:\.\d+){2,3}$/H]]
local user_agent_mozilla	= string.format('(%s) & !(%s) & !(%s) & !(%s)', user_agent_mozilla5, user_agent_thunderbird, user_agent_seamonkey, user_agent_postbox)
-- Mozilla based common Message-ID template
local mozilla_msgid_common	= 'Message-ID=/^\\s*<[\\dA-F]{8}\\.\\d{1,7}\\@([^>\\.]+\\.)+[^>\\.]+>$/H'
local mozilla_msgid_common_sec	= 'Message-ID=/^\\s*<[\\da-f]{8}-([\\da-f]{4}-){3}[\\da-f]{12}\\@([^>\\.]+\\.)+[^>\\.]+>$/H'
local mozilla_msgid		= 'Message-ID=/^\\s*<(3[3-9A-F]|[4-9A-F][\\dA-F])[\\dA-F]{6}\\.(\\d0){1,4}\\d\\@([^>\\.]+\\.)+[^>\\.]+>$/H'
-- Summary rule for forged Mozilla Mail Message-ID header
reconf['FORGED_MUA_MOZILLA_MAIL_MSGID'] = {
  re = string.format('(%s) & (%s) & !(%s) & !(%s)', user_agent_mozilla, mozilla_msgid_common, mozilla_msgid, unusable_msgid),
  score = 4.0,
  description = 'Message pretends to be send from Mozilla Mail but has forged Message-ID',
  group = 'mua'
}
reconf['FORGED_MUA_MOZILLA_MAIL_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !(%s) & !(%s) & !(%s)', user_agent_mozilla, mozilla_msgid_common, mozilla_msgid, unusable_msgid),
  score = 2.5,
  description = 'Message pretends to be send from Mozilla Mail but has forged Message-ID',
  group = 'mua'
}

-- Summary rule for forged Thunderbird Message-ID header
reconf['FORGED_MUA_THUNDERBIRD_MSGID'] = {
  re = string.format('(%s) & (%s) & !(%s) & !(%s)', user_agent_thunderbird, mozilla_msgid_common, mozilla_msgid, unusable_msgid),
  score = 4.0,
  description = 'Forged mail pretending to be from Mozilla Thunderbird but has forged Message-ID',
  group = 'mua'
}
reconf['FORGED_MUA_THUNDERBIRD_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !((%s) | (%s)) & !(%s) & !(%s)', user_agent_thunderbird, mozilla_msgid_common, mozilla_msgid_common_sec, mozilla_msgid, unusable_msgid),
  score = 2.5,
  description = 'Forged mail pretending to be from Mozilla Thunderbird but has forged Message-ID',
  group = 'mua'
}
-- Summary rule for forged Seamonkey Message-ID header
reconf['FORGED_MUA_SEAMONKEY_MSGID'] = {
  re = string.format('(%s) & (%s) & !(%s) & !(%s)', user_agent_seamonkey, mozilla_msgid_common, mozilla_msgid, unusable_msgid),
  score = 4.0,
  description = 'Forged mail pretending to be from Mozilla Seamonkey but has forged Message-ID',
  group = 'mua'
}
reconf['FORGED_MUA_SEAMONKEY_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !((%s) | (%s)) & !(%s) & !(%s)', user_agent_seamonkey, mozilla_msgid_common, mozilla_msgid_common_sec, mozilla_msgid, unusable_msgid),
  score = 2.5,
  description = 'Forged mail pretending to be from Mozilla Seamonkey but has forged Message-ID',
  group = 'mua'
}
-- Summary rule for forged Postbox Message-ID header
reconf['FORGED_MUA_POSTBOX_MSGID'] = {
  re = string.format('(%s) & (%s) & !(%s) & !(%s)', user_agent_postbox, mozilla_msgid_common, mozilla_msgid, unusable_msgid),
  score = 4.0,
  description = 'Forged mail pretending to be from Postbox but has forged Message-ID',
  group = 'mua'
}
reconf['FORGED_MUA_POSTBOX_MSGID_UNKNOWN'] = {
  re = string.format('(%s) & !((%s) | (%s)) & !(%s) & !(%s)', user_agent_postbox, mozilla_msgid_common, mozilla_msgid_common_sec, mozilla_msgid, unusable_msgid),
  score = 2.5,
  description = 'Forged mail pretending to be from Postbox but has forged Message-ID',
  group = 'mua'
}


-- Message id validity
local sane_msgid = 'Message-Id=/^<?[^<>\\\\ \\t\\n\\r\\x0b\\x80-\\xff]+\\@[^<>\\\\ \\t\\n\\r\\x0b\\x80-\\xff]+>?\\s*$/H'
local msgid_comment = 'Message-Id=/\\(.*\\)/H'
reconf['INVALID_MSGID'] = {
  re = string.format('(%s) & !((%s) | (%s))', has_mid, sane_msgid, msgid_comment),
  score = 1.7,
  description = 'Message id is incorrect',
  group = 'headers'
}


-- Only Content-Type header without other MIME headers
local cd = 'header_exists(Content-Disposition)'
local cte = 'header_exists(Content-Transfer-Encoding)'
local ct = 'header_exists(Content-Type)'
local mime_version = 'raw_header_exists(MIME-Version)'
local ct_text_plain = 'content_type_is_type(text) & content_type_is_subtype(plain)'
reconf['MIME_HEADER_CTYPE_ONLY'] = {
  re = string.format('!(%s) & !(%s) & (%s) & !(%s) & !(%s)', cd, cte, ct, mime_version, ct_text_plain),
  score = 2.0,
  description = 'Only Content-Type header without other MIME headers',
  group = 'headers'
}


-- Forged Exchange messages
local msgid_dollars_ok = 'Message-Id=/[0-9a-f]{4,}\\$[0-9a-f]{4,}\\$[0-9a-f]{4,}\\@\\S+/H'
local mimeole_ms = 'X-MimeOLE=/^Produced By Microsoft MimeOLE/H'
local rcvd_with_exchange = 'Received=/with Microsoft Exchange Server/H'
reconf['RATWARE_MS_HASH'] = {
  re = string.format('(%s) & !(%s) & !(%s)', msgid_dollars_ok, mimeole_ms, rcvd_with_exchange),
  score = 2.0,
  description = 'Forged Exchange messages',
  group = 'headers'
}

-- Reply-type in content-type
reconf['STOX_REPLY_TYPE'] = {
  re = 'Content-Type=/text\\/plain; .* reply-type=original/H',
  score = 1.0,
  description = 'Reply-type in content-type',
  group = 'headers'
}

-- Forged yahoo msgid
local at_yahoo_msgid = 'Message-Id=/\\@yahoo\\.com\\b/iH'
local from_yahoo_com = 'From=/\\@yahoo\\.com\\b/iH'
reconf['FORGED_MSGID_YAHOO'] = {
  re = string.format('(%s) & !(%s)', at_yahoo_msgid, from_yahoo_com),
  score = 2.0,
  description = 'Forged yahoo msgid',
  group = 'headers'
}

-- Forged The Bat! MUA headers
local thebat_mua_v1 = 'X-Mailer=/^The Bat! \\(v1\\./H'
local ctype_has_boundary = 'Content-Type=/boundary/iH'
local bat_boundary = 'Content-Type=/boundary=\\"?-{10}/H'
local mailman_21 = 'X-Mailman-Version=/\\d/H'
reconf['FORGED_MUA_THEBAT_BOUN'] = {
  re = string.format('(%s) & (%s) & !(%s) & !(%s)', thebat_mua_v1, ctype_has_boundary, bat_boundary, mailman_21),
  score = 2.0,
  description = 'Forged The Bat! MUA headers',
  group = 'headers'
}

-- Detect Mail.Ru web-mail
local xm_mail_ru_mailer_1_0 = 'X-Mailer=/^Mail\\.Ru Mailer 1\\.0$/H'
local rcvd_e_mail_ru = 'Received=/^(?:from \\[\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\] )?by e\\.mail\\.ru with HTTP;/mH'
reconf['MAIL_RU_MAILER'] = {
  re = string.format('(%s) & (%s)', xm_mail_ru_mailer_1_0, rcvd_e_mail_ru),
  score = 0.0,
  description = 'Sent with Mail.Ru web-mail',
  group = 'headers'
}

-- Detect yandex.ru web-mail
local xm_yandex_ru_mailer_5_0 = 'X-Mailer=/^Yamail \\[ http:\\/\\/yandex\\.ru \\] 5\\.0$/H'
local rcvd_web_yandex_ru = 'Received=/^by web\\d{1,2}[a-z]\\.yandex\\.ru with HTTP;/mH'
reconf['YANDEX_RU_MAILER'] = {
  re = string.format('(%s) & (%s)', xm_yandex_ru_mailer_5_0, rcvd_web_yandex_ru),
  score = 0.0,
  description = 'Sent with yandex.ru web-mail',
  group = 'headers'
}

-- Detect 1C v8.2 and v8.3 mailers
reconf['MAILER_1C_8'] = {
  re = 'X-Mailer=/^1C:Enterprise 8\\.[23]$/H',
  score = 0.0,
  description = 'Sent with 1C:Enterprise 8',
  group = 'headers'
}

-- Detect rogue 'strongmail' MTA with IPv4 and '(-)' in Received line
reconf['STRONGMAIL'] = {
  re = [[Received=/^from\s+strongmail\s+\(\[\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\]\) by \S+ \(-\); /mH]],
  score = 6.0,
  description = 'Sent via rogue "strongmail" MTA',
  group = 'headers'
}

-- Two received headers with ip addresses
local double_ip_spam_1 = 'Received=/from \\[\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\] by \\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3} with/H'
local double_ip_spam_2 = 'Received=/from\\s+\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\s+by\\s+\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3};/H'
reconf['RCVD_DOUBLE_IP_SPAM'] = {
  re = string.format('(%s) | (%s)', double_ip_spam_1, double_ip_spam_2),
  score = 2.0,
  description = 'Two received headers with ip addresses',
  group = 'headers'
}

-- Quoted reply-to from yahoo (seems to be forged)
local repto_quote = 'Reply-To=/\\".*\\"\\s*\\</H'
reconf['REPTO_QUOTE_YAHOO'] = {
  re = string.format('(%s) & ((%s) | (%s))', repto_quote, from_yahoo_com, at_yahoo_msgid),
  score = 2.0,
  description = 'Quoted reply-to from yahoo (seems to be forged)',
  group = 'headers'
}

reconf['FAKE_REPLY'] = {
  re = [[Subject=/^re:/i{header} & !(header_exists(In-Reply-To) | header_exists(References))]],
  description = 'Fake reply',
  score = 1.0,
  group = 'headers'
}

-- Mime-OLE is needed but absent (e.g. fake Outlook or fake Exchange)
local has_msmail_pri = 'header_exists(X-MSMail-Priority)'
local has_mimeole = 'header_exists(X-MimeOLE)'
local has_squirrelmail_in_mailer = 'X-Mailer=/SquirrelMail\\b/H'
local has_office_version_in_mailer = [[X-Mailer=/^Microsoft (?:Office )?Outlook [12]\d\.0/]]
reconf['MISSING_MIMEOLE'] = {
  re = string.format('(%s) & !(%s) & !(%s) & !(%s)',
      has_msmail_pri,
      has_mimeole,
      has_squirrelmail_in_mailer,
      has_office_version_in_mailer),
  score = 2.0,
  description = 'Mime-OLE is needed but absent (e.g. fake Outlook or fake Exchange)',
  group = 'headers'
}

-- Empty delimiters between header names and header values
local function gen_check_header_delimiter_empty(header_name)
  return function(task)
    for _,rh in ipairs(task:get_header_full(header_name) or {}) do
      if rh['empty_separator'] then return true end
    end
    return false
  end
end
reconf['HEADER_FROM_EMPTY_DELIMITER'] = {
  re = string.format('(%s)', 'lua:check_from_delim_empty'),
  score = 1.0,
  description = 'Header From has no delimiter between header name and header value',
  group = 'headers',
  functions = {
    check_from_delim_empty = gen_check_header_delimiter_empty('From')
  }
}
reconf['HEADER_TO_EMPTY_DELIMITER'] = {
  re = string.format('(%s)', 'lua:check_to_delim_empty'),
  score = 1.0,
  description = 'Header To has no delimiter between header name and header value',
  group = 'headers',
  functions = {
    check_to_delim_empty = gen_check_header_delimiter_empty('To')
  }
}
reconf['HEADER_CC_EMPTY_DELIMITER'] = {
  re = string.format('(%s)', 'lua:check_cc_delim_empty'),
  score = 1.0,
  description = 'Header Cc has no delimiter between header name and header value',
  group = 'headers',
  functions = {
    check_cc_delim_empty = gen_check_header_delimiter_empty('Cc')
  }
}
reconf['HEADER_REPLYTO_EMPTY_DELIMITER'] = {
  re = string.format('(%s)', 'lua:check_repto_delim_empty'),
  score = 1.0,
  description = 'Header Reply-To has no delimiter between header name and header value',
  group = 'headers',
  functions = {
    check_repto_delim_empty = gen_check_header_delimiter_empty('Reply-To')
  }
}
reconf['HEADER_DATE_EMPTY_DELIMITER'] = {
  re = string.format('(%s)', 'lua:check_date_delim_empty'),
  score = 1.0,
  description = 'Header Date has no delimiter between header name and header value',
  group = 'headers',
  functions = {
    check_date_delim_empty = gen_check_header_delimiter_empty('Date')
  }
}

-- Definitions of received headers regexp
reconf['RCVD_ILLEGAL_CHARS'] = {
  re = 'Received=/[\\x80-\\xff]/X',
  score = 4.0,
  description = 'Header Received has raw illegal character',
  group = 'headers'
}

local MAIL_RU_Return_Path	= 'Return-path=/^\\s*<.+\\@mail\\.ru>$/iX'
local MAIL_RU_X_Envelope_From	= 'X-Envelope-From=/^\\s*<.+\\@mail\\.ru>$/iX'
local MAIL_RU_From		= 'From=/\\@mail\\.ru>?$/iX'
local MAIL_RU_Received		= 'Received=/from mail\\.ru \\(/mH'

reconf['FAKE_RECEIVED_mail_ru'] = {
  re = string.format('(%s) & !(((%s) | (%s)) & (%s))',
      MAIL_RU_Received, MAIL_RU_Return_Path, MAIL_RU_X_Envelope_From, MAIL_RU_From),
  score = 4.0,
  description = 'Fake helo mail.ru in header Received from non mail.ru sender address',
  group = 'headers'
}

local GMAIL_COM_Return_Path	= 'Return-path=/^\\s*<.+\\@gmail\\.com>$/iX'
local GMAIL_COM_X_Envelope_From	= 'X-Envelope-From=/^\\s*<.+\\@gmail\\.com>$/iX'
local GMAIL_COM_From		= 'From=/\\@gmail\\.com>?$/iX'

local UKR_NET_Return_Path	= 'Return-path=/^\\s*<.+\\@ukr\\.net>$/iX'
local UKR_NET_X_Envelope_From	= 'X-Envelope-From=/^\\s*<.+\\@ukr\\.net>$/iX'
local UKR_NET_From		= 'From=/\\@ukr\\.net>?$/iX'

local RECEIVED_smtp_yandex_ru_1	= 'Received=/from \\[\\d+\\.\\d+\\.\\d+\\.\\d+\\] \\((port=\\d+ )?helo=smtp\\.yandex\\.ru\\)/iX'
local RECEIVED_smtp_yandex_ru_2	= 'Received=/from \\[UNAVAILABLE\\] \\(\\[\\d+\\.\\d+\\.\\d+\\.\\d+\\]:\\d+ helo=smtp\\.yandex\\.ru\\)/iX'
local RECEIVED_smtp_yandex_ru_3	= 'Received=/from \\S+ \\(\\[\\d+\\.\\d+\\.\\d+\\.\\d+\\]:\\d+ helo=smtp\\.yandex\\.ru\\)/iX'
local RECEIVED_smtp_yandex_ru_4	= 'Received=/from \\[\\d+\\.\\d+\\.\\d+\\.\\d+\\] \\(account \\S+ HELO smtp\\.yandex\\.ru\\)/iX'
local RECEIVED_smtp_yandex_ru_5	= 'Received=/from smtp\\.yandex\\.ru \\(\\[\\d+\\.\\d+\\.\\d+\\.\\d+\\]\\)/iX'
local RECEIVED_smtp_yandex_ru_6	= 'Received=/from smtp\\.yandex\\.ru \\(\\S+ \\[\\d+\\.\\d+\\.\\d+\\.\\d+\\]\\)/iX'
local RECEIVED_smtp_yandex_ru_7	= 'Received=/from \\S+ \\(HELO smtp\\.yandex\\.ru\\) \\(\\S+\\@\\d+\\.\\d+\\.\\d+\\.\\d+\\)/iX'
local RECEIVED_smtp_yandex_ru_8	= 'Received=/from \\S+ \\(HELO smtp\\.yandex\\.ru\\) \\(\\d+\\.\\d+\\.\\d+\\.\\d+\\)/iX'
local RECEIVED_smtp_yandex_ru_9	= 'Received=/from \\S+ \\(\\[\\d+\\.\\d+\\.\\d+\\.\\d+\\] helo=smtp\\.yandex\\.ru\\)/iX'

reconf['FAKE_RECEIVED_smtp_yandex_ru'] = {
  re = string.format('(((%s) & ((%s) | (%s))) | ((%s) & ((%s) | (%s))) '..
      ' | ((%s) & ((%s) | (%s)))) & (%s) | (%s) | (%s) | (%s) | (%s) | (%s) | (%s) | (%s) | (%s)',
      MAIL_RU_From, MAIL_RU_Return_Path, MAIL_RU_X_Envelope_From, GMAIL_COM_From,
      GMAIL_COM_Return_Path, GMAIL_COM_X_Envelope_From, UKR_NET_From, UKR_NET_Return_Path,
      UKR_NET_X_Envelope_From, RECEIVED_smtp_yandex_ru_1, RECEIVED_smtp_yandex_ru_2,
      RECEIVED_smtp_yandex_ru_3, RECEIVED_smtp_yandex_ru_4, RECEIVED_smtp_yandex_ru_5,
      RECEIVED_smtp_yandex_ru_6, RECEIVED_smtp_yandex_ru_7, RECEIVED_smtp_yandex_ru_8,
      RECEIVED_smtp_yandex_ru_9),
  score = 4.0,
  description = 'Fake smtp.yandex.ru Received',
  group = 'headers'
}

reconf['FORGED_GENERIC_RECEIVED'] = {
  re = 'Received=/^\\s*(.+\\n)*from \\[\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\] by (([\\w\\d-]+\\.)+[a-zA-Z]{2,6}|\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}); \\w{3}, \\d+ \\w{3} 20\\d\\d \\d\\d\\:\\d\\d\\:\\d\\d [+-]\\d\\d\\d0/X',
  score = 3.6,
  description = 'Forged generic Received',
  group = 'headers'
}

reconf['FORGED_GENERIC_RECEIVED2'] = {
  re = 'Received=/^\\s*(.+\\n)*from \\[\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\] by ([\\w\\d-]+\\.)+[a-z]{2,6} id [\\w\\d]{12}; \\w{3}, \\d+ \\w{3} 20\\d\\d \\d\\d\\:\\d\\d\\:\\d\\d [+-]\\d\\d\\d0/X',
  score = 3.6,
  description = 'Forged generic Received',
  group = 'headers'
}

reconf['FORGED_GENERIC_RECEIVED3'] = {
  re = 'Received=/^\\s*(.+\\n)*by \\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3} with SMTP id [a-zA-Z]{14}\\.\\d{13};[\\r\\n\\s]*\\w{3}, \\d+ \\w{3} 20\\d\\d \\d\\d\\:\\d\\d\\:\\d\\d [+-]\\d\\d\\d0 \\(GMT\\)/X',
  score = 3.6,
  description = 'Forged generic Received',
  group = 'headers'
}

reconf['FORGED_GENERIC_RECEIVED4'] = {
  re = 'Received=/^\\s*(.+\\n)*from localhost by \\S+;\\s+\\w{3}, \\d+ \\w{3} 20\\d\\d \\d\\d\\:\\d\\d\\:\\d\\d [+-]\\d\\d\\d0[\\s\\r\\n]*$/X',
  score = 3.6,
  description = 'Forged generic Received',
  group = 'headers'
}

reconf['INVALID_POSTFIX_RECEIVED'] = {
  re = 'Received=/ \\(Postfix\\) with ESMTP id [A-Z\\d]+([\\s\\r\\n]+for <\\S+?>)?;[\\s\\r\\n]*[A-Z][a-z]{2}, \\d{1,2} [A-Z][a-z]{2} \\d\\d\\d\\d \\d\\d:\\d\\d:\\d\\d [\\+\\-]\\d\\d\\d\\d$/X',
  score = 3.0,
  description = 'Invalid Postfix Received',
  group = 'headers'
}

reconf['X_PHP_FORGED_0X'] = {
  re = "X-PHP-Originating-Script=/^0\\d/X",
  score = 4.0,
  description = "X-PHP-Originating-Script header appears forged",
  group = 'headers'
}

reconf['GOOGLE_FORWARDING_MID_MISSING'] = {
  re = "Message-ID=/SMTPIN_ADDED_MISSING\\@mx\\.google\\.com>$/X",
  score = 2.5,
  description = "Message was missing Message-ID pre-forwarding",
  group = 'headers'
}

reconf['GOOGLE_FORWARDING_MID_BROKEN'] = {
  re = "Message-ID=/SMTPIN_ADDED_BROKEN\\@mx\\.google\\.com>$/X",
  score = 1.7,
  description = "Message had invalid Message-ID pre-forwarding",
  group = 'headers'
}

reconf['CTE_CASE'] = {
  re = 'Content-Transfer-Encoding=/^[78]B/X',
  description = '[78]Bit .vs. [78]bit',
  score = 0.5,
  group = 'headers'
}

reconf['HAS_INTERSPIRE_SIG'] = {
  re = string.format('((%s) & (%s) & (%s) & (%s)) | (%s)',
      'header_exists(X-Mailer-LID)',
      'header_exists(X-Mailer-RecptId)',
      'header_exists(X-Mailer-SID)',
      'header_exists(X-Mailer-Sent-By)',
      'List-Unsubscribe=/\\/unsubscribe\\.php\\?M=[^&]+&C=[^&]+&L=[^&]+&N=[^>]+>$/Xi'),
  description = "Has Interspire fingerprint",
  score = 1.0,
  group = 'headers'
}

reconf['CT_EXTRA_SEMI'] = {
  re = 'Content-Type=/;$/X',
  description = 'Content-Type ends with a semi-colon',
  score = 1.0,
  group = 'headers'
}

reconf['SUBJECT_ENDS_EXCLAIM'] = {
  re = 'Subject=/!\\s*$/H',
  description = 'Subject ends with an exclamation',
  score = 0.0,
  group = 'headers'
}

reconf['SUBJECT_HAS_EXCLAIM'] = {
  re = string.format('%s & !%s', 'Subject=/!/H', 'Subject=/!\\s*$/H'),
  description = 'Subject contains an exclamation',
  score = 0.0,
  group = 'headers'
}

reconf['SUBJECT_ENDS_QUESTION'] = {
  re = 'Subject=/\\?\\s*$/Hu',
  description = 'Subject ends with a question',
  score = 1.0,
  group = 'headers'
}

reconf['SUBJECT_HAS_QUESTION'] = {
  re = string.format('%s & !%s', 'Subject=/\\?/H', 'Subject=/\\?\\s*$/Hu'),
  description = 'Subject contains a question',
  score = 0.0,
  group = 'headers'
}

reconf['SUBJECT_HAS_CURRENCY'] = {
  re = 'Subject=/[$€$¢¥₽]/Hu',
  description = 'Subject contains currency',
  score = 1.0,
  group = 'headers'
}

reconf['SUBJECT_ENDS_SPACES'] = {
  re = 'Subject=/\\s+$/H',
  description = 'Subject ends with space characters',
  score = 0.5,
  group = 'headers'
}

reconf['HAS_ORG_HEADER'] = {
  re = string.format('%s || %s', 'header_exists(Organization)', 'header_exists(Organisation)'),
  description = 'Has Organization header',
  score = 0.0,
  group = 'headers'
}

reconf['X_PHPOS_FAKE'] = {
  re = 'X-PHP-Originating-Script=/^\\d{7}:/Hi',
  description = 'Fake X-PHP-Originating-Script header',
  score = 3.0,
  group = 'headers'
}

reconf['HAS_XOIP'] = {
  re = "header_exists('X-Originating-IP')",
  description = "Has X-Originating-IP header",
  score = 0.0,
  group = 'headers'
}

reconf['HAS_LIST_UNSUB'] = {
  re = string.format('%s', 'header_exists(List-Unsubscribe)'),
  description = 'Has List-Unsubscribe header',
  score = -0.01,
  group = 'headers'
}

reconf['HAS_GUC_PROXY_URI'] = {
  re = '/\\.googleusercontent\\.com\\/proxy/{url}i',
  description = 'Has googleusercontent.com proxy URI',
  score = 0.01,
  group = 'experimental'
}

reconf['HAS_GOOGLE_REDIR'] = {
  re = '/\\.google\\.com\\/url\\?/{url}i',
  description = 'Has google.com/url redirection',
  score = 0.01,
  group = 'experimental'
}

reconf['XM_UA_NO_VERSION'] = {
  re = string.format('(!%s && !%s) && (%s || %s)',
      'X-Mailer=/https?:/H',
      'User-Agent=/https?:/H',
      'X-Mailer=/^[^0-9]+$/H',
      'User-Agent=/^[^0-9]+$/H'),
  description = 'X-Mailer/User-Agent has no version',
  score = 0.01,
  group = 'experimental'
}

-- X-Mailer for old MUA versions which are forged by spammers
local old_x_mailers = {
  -- Outlook Express 6.0 was last included in Windows XP (EOL 2014).  Windows
  -- XP is still used (in 2020) by relatively small number of internet users,
  -- but this header is widely abused by spammers.
  'Microsoft Outlook Express',
  -- Qualcomm Eudora for Windows 7.1.0.9 was released in 2006
  [[QUALCOMM Windows Eudora (Pro )?Version [1-6]\.]],
  -- The Bat 3.0 was released in 2004
  [[The Bat! \(v[12]\.]],
  -- Can be found in public maillist archives, messages circa 2000
  [[Microsoft Outlook IMO, Build 9\.0\.]],
  -- Outlook 2002 (Office XP)
  [[Microsoft Outlook, Build 10\.]],
  -- Some old Apple iOS versions are used on old devices, match only very old
  -- versions (iOS 4.3.5 buid 8L1 was supported until 2013) and less old
  -- versions frequently seen in spam
  [[i(Phone|Pad) Mail \((?:[1-8][A-L]|12H|13E)]],
}

reconf['OLD_X_MAILER'] = {
  description = 'X-Mailer has a very old MUA version',
  re = string.format('X-Mailer=/^(?:%s)/{header}', table.concat(old_x_mailers, '|')),
  score = 2.0,
  group = 'headers',
}

-- X-Mailer header values which should not occur (in the modern mail) at all
local bad_x_mailers = {
  -- header name repeated in the header value
  [[X-Mailer: ]],
  -- Mozilla Thunderbird uses User-Agent header, not X-Mailer
  -- Early Thunderbird had U-A like:
  -- Mozilla Thunderbird 1.0.2 (Windows/20050317)
  -- Thunderbird 2.0.0.23 (X11/20090812)
  [[(?:Mozilla )?Thunderbird \d]],
  -- Was used by Yahoo Groups in 2000s, no one expected to use this in 2020s
  [[eGroups Message Poster]],
  -- Regexp for genuine iOS X-Mailer is below, anything which doesn't match it,
  -- but starts with 'iPhone Mail' or 'iPad Mail' is likely fake
  [[i(?:Phone|Pad) Mail]],
}
-- Apple iPhone/iPad Mail X-Mailer contains iOS build number, e. g. 9B206, 16H5, 18G5023c
-- https://en.wikipedia.org/wiki/IOS_version_history
local apple_ios_x_mailer = [[i(?:Phone|Pad) Mail \((?:1[AC]|[34][AB]|5[ABCFGH]|7[A-E]|8[ABCEFGHJKL]|9[AB]|\d{2}[A-Z])\d+[a-z]?\)]]

reconf['FORGED_X_MAILER'] = {
  description = 'Forged X-Mailer header',
  re = string.format('X-Mailer=/^(?:%s)/{header} && !X-Mailer=/^%s/{header}',
      table.concat(bad_x_mailers, '|'), apple_ios_x_mailer),
  score = 4.5,
  group = 'headers',
}

-- X-Mailer headers like: 'Internet Mail Service (5.5.2650.21)' are being
-- forged by spammers, but MS Exchange 5.5 is still being used (in 2020) on
-- some mail servers. Example of genuine headers (DC-EXMPL is a hostname which
-- can be a FQDN):
-- Received: by DC-EXMPL with Internet Mail Service (5.5.2656.59)
-- 	id <HKH4BJQX>; Tue, 8 Dec 2020 07:10:54 -0600
-- Message-ID: <E7209F9DB64FCC4BB1051420F0E955DD05C9D59F@DC-EXMPL>
-- X-Mailer: Internet Mail Service (5.5.2656.59)
reconf['FORGED_IMS'] = {
  description = 'Forged X-Mailer: Internet Mail Service',
  re = [[X-Mailer=/^Internet Mail Service \(5\./{header} & !Received=/^by \S+ with Internet Mail Service \(5\./{header}]],
  score = 3.0,
  group = 'headers',
}