From 803e21a9a87c3e1904a542de3575834f5aaa5cb6 Mon Sep 17 00:00:00 2001
From: Andris Reinman <andris@reinman.eu>
Date: Tue, 12 Oct 2021 23:18:17 +0300
Subject: [PATCH] ensure that in-reply-to and message-id headers are stored as
 single strings, not arrays

---
 imap-core/lib/imap-tools.js              |  6 ++++++
 imap-core/lib/indexer/parse-mime-tree.js | 11 ++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/imap-core/lib/imap-tools.js b/imap-core/lib/imap-tools.js
index 5c16f792..36f95189 100644
--- a/imap-core/lib/imap-tools.js
+++ b/imap-core/lib/imap-tools.js
@@ -559,6 +559,12 @@ module.exports.getQueryResponse = function (query, message, options) {
             case 'envelope':
                 if (message.envelope) {
                     value = message.envelope;
+                    // cast invalidly stored In-Reply-To (8) and Message-ID (9) to strings
+                    for (let index of [9, 10]) {
+                        if (value[index] && Array.isArray(value[index])) {
+                            value[index] = value[index].pop() || null;
+                        }
+                    }
                 } else {
                     if (!mimeTree) {
                         mimeTree = indexer.parseMimeTree(message.raw);
diff --git a/imap-core/lib/indexer/parse-mime-tree.js b/imap-core/lib/indexer/parse-mime-tree.js
index 0b371a42..5661508c 100644
--- a/imap-core/lib/indexer/parse-mime-tree.js
+++ b/imap-core/lib/indexer/parse-mime-tree.js
@@ -217,7 +217,16 @@ class MIMEParser {
         });
 
         // ensure single value for selected fields
-        ['content-transfer-encoding', 'content-id', 'content-description', 'content-language', 'content-md5', 'content-location'].forEach(key => {
+        [
+            'in-reply-to',
+            'message-id',
+            'content-transfer-encoding',
+            'content-id',
+            'content-description',
+            'content-language',
+            'content-md5',
+            'content-location'
+        ].forEach(key => {
             if (Array.isArray(this._node.parsedHeader[key])) {
                 this._node.parsedHeader[key] = this._node.parsedHeader[key].pop();
             }