From b245fb07a6f516d223dd5285e4e650224267b760 Mon Sep 17 00:00:00 2001
From: "Adam D. Barratt" <adam@adam-barratt.org.uk>
Date: Mon, 7 Oct 2019 19:31:20 +0100
Subject: [PATCH] eximconf: log information about MIME parts

This provides some useful debugging information. Initially it will be
used to survey the likelihood of legitimate attachments being blocked
if further rules are introduced. For this reason, we only log the
"extension", not the full filename.

Signed-off-by: Adam D. Barratt <adam@adam-barratt.org.uk>
---
 modules/exim/templates/eximconf.erb | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/modules/exim/templates/eximconf.erb b/modules/exim/templates/eximconf.erb
index 1b5a80231..a11e8d5de 100644
--- a/modules/exim/templates/eximconf.erb
+++ b/modules/exim/templates/eximconf.erb
@@ -942,6 +942,14 @@ acl_check_mime:
          condition     = ${if !eq{$acl_m_srb}{false}}
          message       = X-Surbl-Hit: $primary_hostname: $acl_m_srb
 
+  # Dump MIME parts to disk. "default" creates sequentially-named files
+  # in <spool_directory>/scan/<message_id>/ which should then be
+  # automagically unlinked after processing.
+  warn   decode        = default
+
+  # Log some information about attachments for debugging
+  warn   log_message   = MIME part [$mime_part_count] -> [${extract{-1}{.}{${lc:$mime_filename}}}] [$mime_content_type]
+
   accept
 
 <%- end -%>
-- 
2.20.1