Script to handle mail replies

Handle replies by marking bounces and forwarding everything
else to the address specified in the config variable
FORWARD_NONBOUNCE_RESPONSES_TO.

1 files changed, 68 insertions, 0 deletions

diff --git a/script/handle-mail-replies b/script/handle-mail-replies
new file mode 100755
index 000000000..5762ddd31
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+++ b/script/handle-mail-replies
@@ -0,0 +1,68 @@
+#!/usr/bin/ruby
+
+# Handle email responses sent to us.
+#
+# This script is invoked as a pipe command, i.e. with the raw email message on stdin.
+# - If a message is identified as a permanent bounce, the user is marked as having a
+#   bounced address, and will not be sent any more messages.
+# - If a message is identified as an out-of-office autoreply, it is discarded.
+# - Any other messages are forwarded to config.get("FORWARD_NONBOUNCE_RESPONSES_TO")
+
+
+# We want to avoid loading rails unless we need it, so we start by just loading the
+# config file ourselves.
+$alaveteli_dir = File.join(File.dirname(__FILE__), '..')
+$:.push(File.join($alaveteli_dir, "commonlib", "rblib"))
+load "config.rb"
+MySociety::Config.set_file(File.join($alaveteli_dir, 'config', 'general'), true)
+MySociety::Config.load_default
+
+def main
+    load_rails
+    raw_message = $stdin.read
+    pfa = permanently_failed_address(raw_message)
+    if pfa.nil?
+        not_a_bounce(raw_message)
+    else
+        record_bounce(pfa, raw_message)
+    end
+end
+
+def permanently_failed_address(raw_message)
+    message = TMail::Mail.parse(raw_message)
+
+    if message.header_string("Return-Path") == "<>"
+        # Some sort of auto-response
+    
+        # Check for Exim’s X-Failed-Recipients header
+        failed_recipients = message.header_string("X-Failed-Recipients")
+        if !failed_recipients.nil?
+            # The X-Failed-Recipients header contains the email address that failed
+            # Check for the words "This is a permanent error." in the body, to indicate
+            # a permanent failure
+            if message.body =~ /This is a permanent error./
+                return failed_recipients
+            end
+        end
+        return nil
+    end
+end
+
+def not_a_bounce(raw_message)
+    forward_non_bounces_to = MySociety::Config.get("FORWARD_NONBOUNCE_RESPONSES_TO", "user-support@localhost")
+    IO.popen("/usr/sbin/sendmail -i #{forward_non_bounces_to}", "w") do |f|
+        f.write(raw_message);
+        f.close;
+    end
+end
+
+def load_rails
+    require File.join($alaveteli_dir, 'config', 'boot')
+    require RAILS_ROOT + '/config/environment'
+end
+
+def record_bounce(email_address, bounce_message)
+    User.record_bounce_for_email(email_address, bounce_message)
+end
+
+main