diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 670f9eea599..aefbe1a16ff 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -1956,10 +1956,10 @@ class MailThread(models.AbstractModel):
 
         for pid, subtypes in new_partners.items():
             subtypes = list(subtypes) if subtypes is not None else None
-            self.message_subscribe(partner_ids=[pid], subtype_ids=subtypes)
+            self.message_subscribe(partner_ids=[pid], subtype_ids=subtypes, force=(subtypes != None))
         for cid, subtypes in new_channels.items():
             subtypes = list(subtypes) if subtypes is not None else None
-            self.message_subscribe(channel_ids=[cid], subtype_ids=subtypes)
+            self.message_subscribe(channel_ids=[cid], subtype_ids=subtypes, force=(subtypes != None))
 
         # remove the current user from the needaction partner to avoid to notify the author of the message
         user_pids = [user_pid for user_pid in user_pids if user_pid != self.env.user.partner_id.id]