+static InternetAddressList *get_sender(GMimeMessage *message)
+{
+ InternetAddressList *reply_to_list;
+
+ reply_to_list = g_mime_message_get_reply_to_list (message);
+ if (reply_to_list &&
+ internet_address_list_length (reply_to_list) > 0) {
+ /*
+ * Some mailing lists munge the Reply-To header despite it
+ * being A Bad Thing, see
+ * http://marc.merlins.org/netrants/reply-to-harmful.html
+ *
+ * The munging is easy to detect, because it results in a
+ * redundant reply-to header, (with an address that already
+ * exists in either To or Cc). So in this case, we ignore the
+ * Reply-To field and use the From header. This ensures the
+ * original sender will get the reply even if not subscribed
+ * to the list. Note that the address in the Reply-To header
+ * will always appear in the reply if reply_all is true.
+ */
+ if (! reply_to_header_is_redundant (message, reply_to_list))
+ return reply_to_list;
+ }
+
+ return g_mime_message_get_from (message);
+}
+
+static InternetAddressList *get_to(GMimeMessage *message)
+{
+ return g_mime_message_get_addresses (message, GMIME_ADDRESS_TYPE_TO);
+}
+
+static InternetAddressList *get_cc(GMimeMessage *message)
+{
+ return g_mime_message_get_addresses (message, GMIME_ADDRESS_TYPE_CC);
+}
+
+static InternetAddressList *get_bcc(GMimeMessage *message)
+{
+ return g_mime_message_get_addresses (message, GMIME_ADDRESS_TYPE_BCC);
+}
+
+/* Augment the recipients of 'reply' from the "Reply-to:", "From:",
+ * "To:", "Cc:", and "Bcc:" headers of 'message'.
+ *
+ * If 'reply_all' is true, use sender and all recipients, otherwise
+ * scan the headers for the first that contains something other than
+ * the user's addresses and add the recipients from this header
+ * (typically this would be reply-to-sender, but also handles reply to
+ * user's own message in a sensible way).
+ *
+ * If any of the user's addresses were found in these headers, the
+ * first of these returned, otherwise NULL is returned.
+ */
+static const char *
+add_recipients_from_message (GMimeMessage *reply,
+ notmuch_config_t *config,
+ GMimeMessage *message,
+ bool reply_all)
+{
+ struct {
+ InternetAddressList * (*get_header)(GMimeMessage *message);
+ GMimeAddressType recipient_type;
+ } reply_to_map[] = {
+ { get_sender, GMIME_ADDRESS_TYPE_TO },
+ { get_to, GMIME_ADDRESS_TYPE_TO },
+ { get_cc, GMIME_ADDRESS_TYPE_CC },
+ { get_bcc, GMIME_ADDRESS_TYPE_BCC },
+ };
+ const char *from_addr = NULL;
+ unsigned int i;
+ unsigned int n = 0;
+
+ for (i = 0; i < ARRAY_SIZE (reply_to_map); i++) {
+ InternetAddressList *recipients;
+
+ recipients = reply_to_map[i].get_header (message);
+
+ n += scan_address_list (recipients, config, reply,
+ reply_to_map[i].recipient_type, &from_addr);
+
+ if (!reply_all && n) {
+ /* Stop adding new recipients in reply-to-sender mode if
+ * we have added some recipient(s) above.
+ *
+ * This also handles the case of user replying to his own
+ * message, where reply-to/from is not a recipient. In
+ * this case there may be more than one recipient even if
+ * not replying to all.
+ */
+ reply = NULL;
+
+ /* From address and some recipients are enough, bail out. */
+ if (from_addr)
+ break;
+ }
+ }
+
+ /* If no recipients were added but we found one of the user's
+ * addresses to use as a from address then the message is from the
+ * user to the user - add the discovered from address to the list
+ * of recipients so that the reply goes back to the user.
+ */
+ if (n == 0 && from_addr)
+ g_mime_message_add_mailbox (reply, GMIME_ADDRESS_TYPE_TO, NULL, from_addr);
+
+ return from_addr;
+}
+
+/*
+ * Look for the user's address in " for <email@add.res>" in the
+ * received headers.