diff --git a/odoo/addons/base/models/ir_mail_server.py b/odoo/addons/base/models/ir_mail_server.py
index 18e8d982ba9..7bd72171205 100644
--- a/odoo/addons/base/models/ir_mail_server.py
+++ b/odoo/addons/base/models/ir_mail_server.py
@@ -437,6 +437,51 @@ class IrMailServer(models.Model):
             return "%s@%s" % (email_from, domain)
         return tools.config.get("email_from")
 
+    def _prepare_email_message(self, message):
+        """Prepare the SMTP information (from, to, message) before sending.
+
+        :param message: the email.message.Message to send, information like the
+            Return-Path, the From, etc... will be used to find the smtp_from and to smtp_to
+        :return: smtp_from, smtp_to_list, message
+            smtp_from: email to used during the authentication to the mail server
+            smtp_to_list: list of email address which will receive the email
+            message: the email.message.Message to send
+        """
+
+        # Use the default bounce address **only if** no Return-Path was
+        # provided by caller.  Caller may be using Variable Envelope Return
+        # Path (VERP) to detect no-longer valid email addresses.
+        smtp_from = message['Return-Path'] or self._get_default_bounce_address() or message['From']
+        assert smtp_from, "The Return-Path or From header is required for any outbound email"
+
+        # The email's "Envelope From" (Return-Path), and all recipient addresses must only contain ASCII characters.
+        from_rfc2822 = extract_rfc2822_addresses(smtp_from)
+        assert from_rfc2822, ("Malformed 'Return-Path' or 'From' address: %r - "
+                              "It should contain one valid plain ASCII email") % smtp_from
+        # use last extracted email, to support rarities like 'Support@MyComp <support@mycompany.com>'
+        smtp_from = from_rfc2822[-1]
+        email_to = message['To']
+        email_cc = message['Cc']
+        email_bcc = message['Bcc']
+        del message['Bcc']
+
+        smtp_to_list = [
+            address
+            for base in [email_to, email_cc, email_bcc]
+            for address in extract_rfc2822_addresses(base)
+            if address
+        ]
+        assert smtp_to_list, self.NO_VALID_RECIPIENT
+
+        x_forge_to = message['X-Forge-To']
+        if x_forge_to:
+            # `To:` header forged, e.g. for posting on mail.channels, to avoid confusion
+            del message['X-Forge-To']
+            del message['To']           # avoid multiple To: headers!
+            message['To'] = x_forge_to
+
+        return smtp_from, smtp_to_list, message
+
     @api.model
     def send_email(self, message, mail_server_id=None, smtp_server=None, smtp_port=None,
                    smtp_user=None, smtp_password=None, smtp_encryption=None,
@@ -473,37 +518,7 @@ class IrMailServer(models.Model):
         :return: the Message-ID of the message that was just sent, if successfully sent, otherwise raises
                  MailDeliveryException and logs root cause.
         """
-        # Use the default bounce address **only if** no Return-Path was
-        # provided by caller.  Caller may be using Variable Envelope Return
-        # Path (VERP) to detect no-longer valid email addresses.
-        smtp_from = message['Return-Path'] or self._get_default_bounce_address() or message['From']
-        assert smtp_from, "The Return-Path or From header is required for any outbound email"
-
-        # The email's "Envelope From" (Return-Path), and all recipient addresses must only contain ASCII characters.
-        from_rfc2822 = extract_rfc2822_addresses(smtp_from)
-        assert from_rfc2822, ("Malformed 'Return-Path' or 'From' address: %r - "
-                              "It should contain one valid plain ASCII email") % smtp_from
-        # use last extracted email, to support rarities like 'Support@MyComp <support@mycompany.com>'
-        smtp_from = from_rfc2822[-1]
-        email_to = message['To']
-        email_cc = message['Cc']
-        email_bcc = message['Bcc']
-        del message['Bcc']
-
-        smtp_to_list = [
-            address
-            for base in [email_to, email_cc, email_bcc]
-            for address in extract_rfc2822_addresses(base)
-            if address
-        ]
-        assert smtp_to_list, self.NO_VALID_RECIPIENT
-
-        x_forge_to = message['X-Forge-To']
-        if x_forge_to:
-            # `To:` header forged, e.g. for posting on mail.channels, to avoid confusion
-            del message['X-Forge-To']
-            del message['To']           # avoid multiple To: headers!
-            message['To'] = x_forge_to
+        smtp_from, smtp_to_list, message = self._prepare_email_message(message)
 
         # Do not actually send emails in testing mode!
         if getattr(threading.currentThread(), 'testing', False) or self.env.registry.in_test_mode():