plone · Manik-Khajuria-5 · Feb 2, 2026
diff --git a/news/1956.bugfix.rst b/news/1956.bugfix.rst
@@ -0,0 +1 @@
+Ensure @email-send adds message intro ONLY for non-multipart messages. Fixes #1956.
diff --git a/src/plone/restapi/services/email_send/post.py b/src/plone/restapi/services/email_send/post.py
@@ -105,9 +105,14 @@ def reply(self):
             )
         )
 
-        message = f"{message_intro} \n {message}"
+        if not isinstance(message, str):
+            message = str(message)
 
         message = message_from_string(message)
+        if not message.is_multipart():
+            payload = message.get_payload()
+            message.set_payload(f"{message_intro}\n\n{payload}")
+
         message["Reply-To"] = sender_from_address
         try:
             host.send(

diff --git a/src/plone/restapi/tests/test_services_email_send.py b/src/plone/restapi/tests/test_services_email_send.py
@@ -1,3 +1,6 @@
+from email import message_from_string
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
 from plone.app.testing import setRoles
 from plone.app.testing import SITE_OWNER_NAME
 from plone.app.testing import SITE_OWNER_PASSWORD
@@ -98,3 +101,159 @@ def test_email_send_anonymous(self):
         )
 
         self.assertEqual(response.status_code, 401)
+
+    def test_email_send_plain_text_has_intro(self):
+        response = self.api_session.post(
+            "/@email-send",
+            json={
+                "to": "jane@doe.com",
+                "from": "john@doe.com",
+                "message": "This is a plain text message.",
+                "name": "John Doe",
+                "subject": "Test Subject",
+            },
+        )
+        transaction.commit()
+
+        self.assertEqual(response.status_code, 204)
+        msg = self.mailhost.messages[0]
+        if isinstance(msg, bytes) and bytes is not str:
+            msg = msg.decode("utf-8")
+
+        self.assertTrue("You are receiving this mail because" in msg)
+        self.assertTrue("John Doe" in msg)
+        self.assertTrue("This is a plain text message." in msg)
+        intro_pos = msg.find("You are receiving this mail because")
+        message_pos = msg.find("This is a plain text message.")
+        self.assertGreater(
+            message_pos, intro_pos, "Intro text should appear before message"
+        )
+
+    def test_email_send_multipart_no_intro(self):
+        multipart_msg = MIMEMultipart("alternative")
+        multipart_msg["Subject"] = "Test Multipart"
+        multipart_msg["From"] = "sender@example.com"
+        multipart_msg["To"] = "recipient@example.com"
+
+        text_part = MIMEText("This is the plain text version.", "plain")
+        html_part = MIMEText(
+            "<html><body>This is the <b>HTML</b> version.</body></html>", "html"
+        )
+
+        multipart_msg.attach(text_part)
+        multipart_msg.attach(html_part)
+
+        message_str = multipart_msg.as_string()
+
+        response = self.api_session.post(
+            "/@email-send",
+            json={
+                "to": "jane@doe.com",
+                "from": "john@doe.com",
+                "message": message_str,
+                "name": "John Doe",
+                "subject": "Test Multipart Subject",
+            },
+        )
+        transaction.commit()
+
+        self.assertEqual(response.status_code, 204)
+        msg = self.mailhost.messages[0]
+        if isinstance(msg, bytes) and bytes is not str:
+            msg = msg.decode("utf-8")
+
+        self.assertFalse("You are receiving this mail because" in msg)
+        self.assertTrue("multipart/alternative" in msg)
+        self.assertTrue("This is the plain text version." in msg)
+        self.assertTrue("This is the <b>HTML</b> version." in msg)
+
+    def test_email_send_multipart_structure_preserved(self):
+        multipart_msg = MIMEMultipart("alternative")
+        text_part = MIMEText("Plain text content here.", "plain")
+        html_part = MIMEText(
+            "<html><body><p>HTML content here.</p></body></html>", "html"
+        )
+
+        multipart_msg.attach(text_part)
+        multipart_msg.attach(html_part)
+
+        message_str = multipart_msg.as_string()
+
+        response = self.api_session.post(
+            "/@email-send",
+            json={
+                "to": "jane@doe.com",
+                "from": "john@doe.com",
+                "message": message_str,
+                "subject": "Structure Test",
+            },
+        )
+        transaction.commit()
+
+        self.assertEqual(response.status_code, 204)
+        msg = self.mailhost.messages[0]
+        if isinstance(msg, bytes) and bytes is not str:
+            msg = msg.decode("utf-8")
+
+        parsed_msg = message_from_string(msg)
+
+        self.assertTrue(parsed_msg.is_multipart())
+        self.assertTrue("multipart/alternative" in parsed_msg.get_content_type())
+        parts = list(parsed_msg.walk())
+        self.assertEqual(len(parts), 3)
+        text_found = False
+        html_found = False
+        for part in parts:
+            if part.get_content_type() == "text/plain":
+                self.assertTrue("Plain text content here." in part.get_payload())
+                text_found = True
+            elif part.get_content_type() == "text/html":
+                self.assertTrue("HTML content here." in part.get_payload())
+                html_found = True
+        self.assertTrue(text_found, "Text part not found")
+        self.assertTrue(html_found, "HTML part not found")
+
+    def test_email_send_multipart_with_attachment(self):
+        """Test that multipart messages with attachments are handled correctly."""
+        from email import encoders
+        from email.mime.base import MIMEBase
+
+        multipart_msg = MIMEMultipart()
+        multipart_msg["Subject"] = "Test with Attachment"
+        multipart_msg["From"] = "sender@example.com"
+        multipart_msg["To"] = "recipient@example.com"
+
+        text_part = MIMEText("This message has an attachment.", "plain")
+        multipart_msg.attach(text_part)
+
+        attachment = MIMEBase("application", "octet-stream")
+        attachment.set_payload(b"Test attachment content")
+        encoders.encode_base64(attachment)
+        attachment.add_header(
+            "Content-Disposition",
+            'attachment; filename="test.txt"',
+        )
+        multipart_msg.attach(attachment)
+
+        message_str = multipart_msg.as_string()
+
+        response = self.api_session.post(
+            "/@email-send",
+            json={
+                "to": "jane@doe.com",
+                "from": "john@doe.com",
+                "message": message_str,
+                "subject": "Attachment Test",
+            },
+        )
+        transaction.commit()
+
+        self.assertEqual(response.status_code, 204)
+        msg = self.mailhost.messages[0]
+        if isinstance(msg, bytes) and bytes is not str:
+            msg = msg.decode("utf-8")
+
+        self.assertFalse("You are receiving this mail because" in msg)
+        self.assertTrue("multipart" in msg.lower())
+        self.assertTrue("Content-Disposition" in msg)
+        self.assertTrue("attachment" in msg.lower())
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Ensure @email-send adds message intro ONLY for non-multipart messages. Fixes #1956.