diff --git a/README.md b/README.md
index 286ba3b..f9c7d4d 100644
--- a/README.md
+++ b/README.md
@@ -525,6 +525,9 @@ Add to crontab for recurring tickets and maintenance cleanup:
 # Delete orphaned upload files with no attachment row, past a 24h grace period (daily).
 # Add --dry-run to preview without deleting.
 0 4 * * * php /path/to/tinkertickets/scripts/cleanup_orphan_uploads.php
+
+# Retry failed Matrix webhook notifications (exponential backoff, every 5 minutes)
+*/5 * * * * php /path/to/tinkertickets/cron/retry_failed_notifications.php
 ```
 
 ### 3. File Uploads
diff --git a/cron/retry_failed_notifications.php b/cron/retry_failed_notifications.php
new file mode 100644
index 0000000..36e3b19
--- /dev/null
+++ b/cron/retry_failed_notifications.php
@@ -0,0 +1,133 @@
+#!/usr/bin/env php
+<?php
+
+/**
+ * Failed Matrix Notification Retry Cron Job
+ *
+ * NotificationHelper::fire() queues a failed webhook post to
+ * notification_retry_queue instead of just logging and losing it. This
+ * script retries due rows with exponential backoff, up to each row's
+ * max_attempts, then leaves an exhausted row in place (not deleted) so it
+ * remains visible for manual investigation.
+ *
+ * Run this via cron every 5-10 minutes (see README.md's Cron Jobs section
+ * for the exact crontab line — the "every 5 minutes" syntax isn't repeated
+ * here since it would terminate this comment block early).
+ */
+
+// Prevent web access
+if (php_sapi_name() !== 'cli') {
+    http_response_code(403);
+    exit('CLI access only');
+}
+
+chdir(dirname(__DIR__));
+
+require_once 'config/config.php';
+require_once 'helpers/Database.php';
+require_once 'helpers/NotificationHelper.php';
+
+function logMessage($message)
+{
+    echo '[' . date('Y-m-d H:i:s') . '] ' . $message . "\n";
+}
+
+/** Exponential backoff in minutes: 2, 4, 8, 16, 32, capped at 60. */
+function nextAttemptDelayMinutes(int $attemptNumber): int
+{
+    return min(60, 2 ** $attemptNumber);
+}
+
+$webhookUrl = $GLOBALS['config']['MATRIX_WEBHOOK_URL'] ?? null;
+if (empty($webhookUrl)) {
+    logMessage('MATRIX_WEBHOOK_URL not configured — nothing to retry, exiting.');
+    exit(0);
+}
+
+try {
+    $conn = Database::getConnection();
+} catch (Exception $e) {
+    logMessage('FATAL ERROR: could not connect to database: ' . $e->getMessage());
+    exit(1);
+}
+
+// Process a bounded batch per run so one cron tick can't run indefinitely if
+// the queue has backed up.
+$batchLimit = 50;
+
+$stmt = $conn->prepare(
+    "SELECT retry_id, payload, attempts, max_attempts
+       FROM notification_retry_queue
+      WHERE next_attempt_at <= NOW() AND attempts < max_attempts
+      ORDER BY retry_id ASC
+      LIMIT ?"
+);
+$stmt->bind_param('i', $batchLimit);
+$stmt->execute();
+$dueRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
+$stmt->close();
+
+if (empty($dueRows)) {
+    logMessage('No notifications due for retry.');
+    exit(0);
+}
+
+$succeeded = 0;
+$failed = 0;
+$exhausted = 0;
+
+foreach ($dueRows as $row) {
+    $payload = json_decode($row['payload'], true);
+    if (!is_array($payload)) {
+        // Corrupt row — can't retry something unparseable. Remove it rather
+        // than retrying forever against a row that will never succeed.
+        $del = $conn->prepare("DELETE FROM notification_retry_queue WHERE retry_id = ?");
+        $del->bind_param('i', $row['retry_id']);
+        $del->execute();
+        $del->close();
+        logMessage("Discarded retry #{$row['retry_id']}: payload is not valid JSON");
+        continue;
+    }
+
+    $result = NotificationHelper::attemptDelivery($webhookUrl, $payload);
+
+    if ($result['success']) {
+        $del = $conn->prepare("DELETE FROM notification_retry_queue WHERE retry_id = ?");
+        $del->bind_param('i', $row['retry_id']);
+        $del->execute();
+        $del->close();
+        $succeeded++;
+        logMessage("Retry #{$row['retry_id']} succeeded (attempt " . ((int)$row['attempts'] + 1) . ')');
+        continue;
+    }
+
+    $newAttempts = (int)$row['attempts'] + 1;
+    if ($newAttempts >= (int)$row['max_attempts']) {
+        // Exhausted: leave the row (attempts is now == max_attempts, so the
+        // WHERE clause above naturally excludes it from future runs) rather
+        // than deleting it, so it stays visible for manual investigation.
+        $upd = $conn->prepare(
+            "UPDATE notification_retry_queue SET attempts = ?, last_error = ? WHERE retry_id = ?"
+        );
+        $upd->bind_param('isi', $newAttempts, $result['error'], $row['retry_id']);
+        $upd->execute();
+        $upd->close();
+        $exhausted++;
+        logMessage("Retry #{$row['retry_id']} exhausted after {$newAttempts} attempts: {$result['error']}");
+        continue;
+    }
+
+    $delayMinutes = nextAttemptDelayMinutes($newAttempts);
+    $upd = $conn->prepare(
+        "UPDATE notification_retry_queue
+            SET attempts = ?, last_error = ?, next_attempt_at = DATE_ADD(NOW(), INTERVAL ? MINUTE)
+          WHERE retry_id = ?"
+    );
+    $upd->bind_param('isii', $newAttempts, $result['error'], $delayMinutes, $row['retry_id']);
+    $upd->execute();
+    $upd->close();
+    $failed++;
+    logMessage("Retry #{$row['retry_id']} failed (attempt {$newAttempts}), next attempt in {$delayMinutes}m: {$result['error']}");
+}
+
+logMessage("Done: {$succeeded} succeeded, {$failed} rescheduled, {$exhausted} exhausted (of " . count($dueRows) . ' processed)');
diff --git a/helpers/NotificationHelper.php b/helpers/NotificationHelper.php
index f4590e5..6535f2c 100644
--- a/helpers/NotificationHelper.php
+++ b/helpers/NotificationHelper.php
@@ -7,13 +7,16 @@ class NotificationHelper
 {
     // ─── Internal: fire a webhook ─────────────────────────────────────────────
 
-    private static function fire(array $payload): void
+    /**
+     * POST a payload to the configured Matrix webhook and report the raw
+     * result. Shared by fire() (best-effort, queues on failure) and
+     * cron/retry_failed_notifications.php (retries a previously-queued
+     * payload) so both use identical request handling.
+     *
+     * @return array{success: bool, http_code: ?int, error: ?string}
+     */
+    public static function attemptDelivery(string $webhookUrl, array $payload): array
     {
-        $webhookUrl = $GLOBALS['config']['MATRIX_WEBHOOK_URL'] ?? null;
-        if (empty($webhookUrl)) {
-            return;
-        }
-
         $ch = curl_init($webhookUrl);
         curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
         curl_setopt($ch, CURLOPT_POST, 1);
@@ -21,10 +24,11 @@ class NotificationHelper
         curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
         curl_setopt($ch, CURLOPT_TIMEOUT, 10);
         // A slow-but-not-fully-hung hookshot endpoint could otherwise add up
-        // to the full CURLOPT_TIMEOUT per fire() call, and a single request
-        // can call fire() (via notifyWatchers/sendCommentNotification/etc.)
-        // more than once sequentially — capping just the connect phase keeps
-        // that from stacking into tens of seconds of added latency.
+        // to the full CURLOPT_TIMEOUT per call, and a single request can
+        // trigger more than one notification sequentially (via
+        // notifyWatchers/sendCommentNotification/etc.) — capping just the
+        // connect phase keeps that from stacking into tens of seconds of
+        // added latency.
         curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3);
 
         $response  = curl_exec($ch);
@@ -32,12 +36,54 @@ class NotificationHelper
         $curlError = curl_error($ch);
         curl_close($ch);
 
-        $id = $payload['ticket_id'] ?? '?';
         if ($curlError) {
-            error_log("Matrix webhook cURL error for ticket #{$id}: {$curlError}");
-        } elseif ($httpCode < 200 || $httpCode >= 300) {
-            error_log("Matrix webhook failed for ticket #{$id}. HTTP {$httpCode}: {$response}");
+            return ['success' => false, 'http_code' => null, 'error' => $curlError];
         }
+        if ($httpCode < 200 || $httpCode >= 300) {
+            return ['success' => false, 'http_code' => $httpCode, 'error' => "HTTP {$httpCode}: {$response}"];
+        }
+        return ['success' => true, 'http_code' => $httpCode, 'error' => null];
+    }
+
+    /**
+     * Persist a failed payload for later retry by
+     * cron/retry_failed_notifications.php. Best-effort: a DB failure here
+     * must not throw back into the original (already-failed) notification
+     * attempt — it just means this particular failure isn't retried, no
+     * worse than the pre-existing behavior.
+     */
+    private static function queueForRetry(array $payload, string $error): void
+    {
+        try {
+            require_once dirname(__DIR__) . '/helpers/Database.php';
+            $conn = Database::getConnection();
+            $stmt = $conn->prepare(
+                "INSERT INTO notification_retry_queue (payload, last_error) VALUES (?, ?)"
+            );
+            $payloadJson = json_encode($payload);
+            $stmt->bind_param("ss", $payloadJson, $error);
+            $stmt->execute();
+            $stmt->close();
+        } catch (Throwable $e) {
+            error_log('NotificationHelper: failed to queue notification for retry: ' . $e->getMessage());
+        }
+    }
+
+    private static function fire(array $payload): void
+    {
+        $webhookUrl = $GLOBALS['config']['MATRIX_WEBHOOK_URL'] ?? null;
+        if (empty($webhookUrl)) {
+            return;
+        }
+
+        $result = self::attemptDelivery($webhookUrl, $payload);
+        if ($result['success']) {
+            return;
+        }
+
+        $id = $payload['ticket_id'] ?? '?';
+        error_log("Matrix webhook failed for ticket #{$id}: {$result['error']}");
+        self::queueForRetry($payload, $result['error']);
     }
 
     private static function notifyUsers(): array
diff --git a/migrations/007_notification_retry_queue.sql b/migrations/007_notification_retry_queue.sql
new file mode 100644
index 0000000..fa995b8
--- /dev/null
+++ b/migrations/007_notification_retry_queue.sql
@@ -0,0 +1,20 @@
+-- Queue for Matrix webhook notifications that failed to send (#78).
+--
+-- NotificationHelper::fire() previously logged a failed webhook post via
+-- error_log() only, with no retry and no persistent record — once a
+-- notification failed, it was gone. Failed payloads are now queued here and
+-- retried by cron/retry_failed_notifications.php with exponential backoff.
+--
+-- Safe to re-run.
+
+CREATE TABLE IF NOT EXISTS `notification_retry_queue` (
+  `retry_id` int(11) NOT NULL AUTO_INCREMENT,
+  `payload` longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL CHECK (json_valid(`payload`)),
+  `attempts` int(11) NOT NULL DEFAULT 0,
+  `max_attempts` int(11) NOT NULL DEFAULT 6,
+  `next_attempt_at` timestamp NULL DEFAULT current_timestamp(),
+  `last_error` varchar(500) DEFAULT NULL,
+  `created_at` timestamp NULL DEFAULT current_timestamp(),
+  PRIMARY KEY (`retry_id`),
+  KEY `idx_next_attempt` (`next_attempt_at`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;