diff --git a/mail_ux/models/mail_compose_message.py b/mail_ux/models/mail_compose_message.py
index e007e47c..3abc8511 100644
--- a/mail_ux/models/mail_compose_message.py
+++ b/mail_ux/models/mail_compose_message.py
@@ -26,8 +26,14 @@ def _action_send_mail(self, auto_commit=False):
         if not self.env.user.send_message_delay:
             return super()._action_send_mail(auto_commit=auto_commit)
 
-        # Limpiamos __action_done porque odoo guarda una base automation ahi
-        # Al querer crear el mensaje programado falla por mala definicion de contexto (es un objeto y no un str, int, etc.)
-        # No es replicable en odoo porque no tienen base automation para schedulear un mensaje
-        self.with_context(__action_done={})._action_schedule_message()
+        self._action_schedule_message()
         return self.env["mail.mail"].sudo(), self.env["mail.message"]
+
+    def _prepare_schedule_message_post_values(self, post_values):
+        """send_context es un campo Json y base_automation deja en el contexto
+        claves privadas con recordsets (__action_done): no son serializables."""
+        values = super()._prepare_schedule_message_post_values(post_values)
+        values["send_context"] = {
+            key: value for key, value in (values.get("send_context") or {}).items() if not key.startswith("__")
+        }
+        return values
diff --git a/mail_ux/tests/__init__.py b/mail_ux/tests/__init__.py
new file mode 100644
index 00000000..4a4b7227
--- /dev/null
+++ b/mail_ux/tests/__init__.py
@@ -0,0 +1 @@
+from . import test_schedule_message
diff --git a/mail_ux/tests/test_schedule_message.py b/mail_ux/tests/test_schedule_message.py
new file mode 100644
index 00000000..768c7d7a
--- /dev/null
+++ b/mail_ux/tests/test_schedule_message.py
@@ -0,0 +1,34 @@
+from odoo.tests.common import TransactionCase
+
+
+class TestScheduleMessage(TransactionCase):
+    def test_send_context_without_private_keys(self):
+        """send_context is a Json field: a private key holding recordsets
+        (base_automation's __action_done) makes the insert fail."""
+        self.env.user.send_message_delay = 60
+        partner = self.env["res.partner"].create({"name": "Test Schedule"})
+        composer = (
+            self.env["mail.compose.message"]
+            .with_context(
+                **{
+                    "__action_done": {self.env.user: partner},
+                    "lang": "en_US",
+                }
+            )
+            .create(
+                {
+                    "model": "res.partner",
+                    "res_ids": repr(partner.ids),
+                    "subject": "Test",
+                    "body": "<p>Test</p>",
+                }
+            )
+        )
+
+        composer._action_send_mail()
+
+        scheduled = self.env["mail.scheduled.message"].search(
+            [("model", "=", "res.partner"), ("res_id", "=", partner.id)]
+        )
+        self.assertEqual(len(scheduled), 1)
+        self.assertEqual(scheduled.send_context, {"lang": "en_US"})