diff --git a/docs/configuration.md b/docs/configuration.md
index c766605..84cec7c 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -313,6 +313,14 @@ URL to use for attachment and log links. Defaults to `http://IP:PORT`.
 **Default:** `off`  
 If enabled, mod replies will use their nicknames (on the inbox server) instead of their usernames
 
+#### notifyOnMainServerLeave
+**Default:** `on`
+If enabled, a system message will be posted into any open threads if the user leaves a main server
+
+#### notifyOnMainServerJoin
+**Default:** `on`
+If enabled, a system message will be posted into any open threads if the user joins a main server
+
 #### anonymizeChannelName
 **Default:** `off`
 If enabled, channel names will be the user's name and discriminator salted with the current time, then hashed to protect the user's privacy
diff --git a/src/data/cfg.jsdoc.js b/src/data/cfg.jsdoc.js
index 1e1658e..200971a 100644
--- a/src/data/cfg.jsdoc.js
+++ b/src/data/cfg.jsdoc.js
@@ -51,6 +51,8 @@
  * @property {boolean} [reactOnSeen=false]
  * @property {string} [reactOnSeenEmoji="📨"]
  * @property {boolean} [createThreadOnMention=false]
+ * @property {boolean} [notifyOnMainServerLeave=true]
+ * @property {boolean} [notifyOnMainServerJoin=true]
  * @property {number} [port=8890]
  * @property {string} [url]
  * @property {array} [extraIntents=[]]
diff --git a/src/data/cfg.schema.json b/src/data/cfg.schema.json
index 8aa5ba7..1678530 100644
--- a/src/data/cfg.schema.json
+++ b/src/data/cfg.schema.json
@@ -296,6 +296,16 @@
       "default": false
     },
 
+    "notifyOnMainServerLeave": {
+      "$ref": "#/definitions/customBoolean",
+      "default": true
+    },
+
+    "notifyOnMainServerJoin": {
+      "$ref": "#/definitions/customBoolean",
+      "default": true
+    },
+
     "port": {
       "type": "number",
       "maximum": 65535,
diff --git a/src/main.js b/src/main.js
index b1316a9..70d11e8 100644
--- a/src/main.js
+++ b/src/main.js
@@ -28,6 +28,7 @@ const version = require("./modules/version");
 const newthread = require("./modules/newthread");
 const idModule = require("./modules/id");
 const alert = require("./modules/alert");
+const joinLeaveNotification = require("./modules/joinLeaveNotification");
 
 const {ACCIDENTAL_THREAD_MESSAGES} = require("./data/constants");
 
@@ -304,7 +305,8 @@ async function initPlugins() {
     version,
     newthread,
     idModule,
-    alert
+    alert,
+    joinLeaveNotification
   ];
 
   const plugins = [...builtInPlugins];
diff --git a/src/modules/joinLeaveNotification.js b/src/modules/joinLeaveNotification.js
new file mode 100644
index 0000000..970a2f9
--- /dev/null
+++ b/src/modules/joinLeaveNotification.js
@@ -0,0 +1,31 @@
+const config = require("../cfg");
+const threads = require("../data/threads");
+const utils = require("../utils");
+
+module.exports = ({ bot }) => {
+    // Join Notification: Post a message in the thread if the user joins a main server
+    if (config.notifyOnMainServerJoin) {
+        bot.on("guildMemberAdd", async (guild, member) => {
+            const mainGuilds = utils.getMainGuilds();
+            if (! mainGuilds.find(gld => gld.id === guild.id)) return;
+
+            const thread = await threads.findOpenThreadByUserId(member.id);
+            if (thread != null) {
+                await thread.postSystemMessage(`***The user joined the guild ${guild.name}.***`);
+            }
+        });
+    }
+
+    // Leave Notification: Post a message in the thread if the user leaves a main server
+    if (config.notifyOnMainServerLeave) {
+        bot.on("guildMemberRemove", async (guild, member) => {
+            const mainGuilds = utils.getMainGuilds();
+            if (! mainGuilds.find(gld => gld.id === guild.id)) return;
+
+            const thread = await threads.findOpenThreadByUserId(member.id);
+            if (thread != null) {
+                await thread.postSystemMessage(`***The user left the guild ${guild.name}.***`);
+            }
+        });
+    }
+};