diff --git a/addons/mail/tests/test_mail_composer.py b/addons/mail/tests/test_mail_composer.py
index 846c98f8f84..c0ddca184b5 100644
--- a/addons/mail/tests/test_mail_composer.py
+++ b/addons/mail/tests/test_mail_composer.py
@@ -126,9 +126,8 @@ class TestMailComposerForm(TestMailComposer):
         )
         saved_form = form.save()
         self.assertEqual(
-            # saved_form.partner_ids, partner_private + partner_classic,
-            saved_form.partner_ids, partner_classic,
-            'Default value is kept at save (FIXME: loosing private partner)'
+            saved_form.partner_ids, partner_private + partner_classic,
+            'Default value is kept at save'
         )
 
         with self.mock_mail_gateway():
@@ -136,11 +135,7 @@ class TestMailComposerForm(TestMailComposer):
 
         message = self.test_record.message_ids[0]
         self.assertEqual(message.body, '<p>Hello</p>')
-        # self.assertEqual(message.partner_ids, partner_private + partner_classic)
-        self.assertEqual(
-            message.partner_ids, partner_classic,
-            'FIXME: loosing private partner'
-        )
+        self.assertEqual(message.partner_ids, partner_private + partner_classic)
         self.assertEqual(message.subject, f'{test_record.name}')
 
     @mute_logger('odoo.addons.base.models.ir_rule', 'odoo.addons.mail.models.mail_mail')
diff --git a/addons/mail/wizard/mail_compose_message.py b/addons/mail/wizard/mail_compose_message.py
index f766f2019c6..b6ae9990cc2 100644
--- a/addons/mail/wizard/mail_compose_message.py
+++ b/addons/mail/wizard/mail_compose_message.py
@@ -7,6 +7,7 @@ import re
 
 from odoo import _, api, fields, models, tools, Command
 from odoo.exceptions import UserError
+from odoo.osv import expression
 from odoo.tools import email_re
 
 
@@ -87,6 +88,12 @@ class MailComposer(models.TransientModel):
         filtered_result = dict((fname, result[fname]) for fname in result if fname in fields)
         return filtered_result
 
+    def _partner_ids_domain(self):
+        return expression.OR([
+            [('type', '!=', 'private')],
+            [('id', 'in', self.env.context.get('default_partner_ids', []))],
+        ])
+
     # content
     subject = fields.Char('Subject', compute=False)
     body = fields.Html(
@@ -142,7 +149,7 @@ class MailComposer(models.TransientModel):
     partner_ids = fields.Many2many(
         'res.partner', 'mail_compose_message_res_partner_rel',
         'wizard_id', 'partner_id', 'Additional Contacts',
-        domain=[('type', '!=', 'private')])
+        domain=_partner_ids_domain)
     # sending
     auto_delete = fields.Boolean('Delete Emails',
         help='This option permanently removes any track of email after it\'s been sent, including from the Technical menu in the Settings, in order to preserve storage space of your Odoo database.')