diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5bc677..7a01445 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ The format is based on Keep a Changelog and this project adheres to Semantic Ver
 - The `resend` mailer entry in `shared/config/mailer.php` and `RESEND_APIKEY` in `.env.example`.
 - A `save_remote_images()` helper that downloads the demo images in parallel; `php qt demo` uses it.
 - An API smoke test in CI.
+- `logging.message.limit` and `mailer.transport_log_limit` in the config: the number of log messages and transport log lines kept in memory, both `1000` by default (framework #593).
 
 ### Changed
 - `shared/config/lang.php` uses the 3.1 Lang format: `default` adapter (`file`, `deepl` or `google_translate`), `default_locale` and a section per remote adapter.
diff --git a/shared/config/logging.php b/shared/config/logging.php
index 4da0fe7..db7d953 100644
--- a/shared/config/logging.php
+++ b/shared/config/logging.php
@@ -17,4 +17,12 @@
         'path' => logs_dir(),
         'level' => 'warning',
     ],
+
+    /**
+     * In debug mode the web app keeps its log messages in memory for the debug toolbar.
+     * Only the last `limit` messages are kept; 0 keeps every message.
+     */
+    'message' => [
+        'limit' => 1000,
+    ],
 ];
diff --git a/shared/config/mailer.php b/shared/config/mailer.php
index 535c55e..86f2dc2 100644
--- a/shared/config/mailer.php
+++ b/shared/config/mailer.php
@@ -12,6 +12,12 @@
 
     'mail_trap' => true,
 
+    /**
+     * The number of transport log lines the mailer keeps: the SMTP exchange in debug mode
+     * and the errors of failed sends. 0 keeps every line.
+     */
+    'transport_log_limit' => 1000,
+
     'smtp' => [
         'host' => env('MAIL_HOST'),
         'secure' => env('MAIL_SMTP_SECURE'),