diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 913f735d340..4d2fec269f5 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1389,7 +1389,7 @@ en:
     email_prefix: "The [label] used in the subject of emails. It will default to 'title' if not set."
     email_site_title: "The title of the site used as the sender of emails from the site. Default to 'title' if not set. If your 'title' contains characters that are not allowed in email sender strings, use this setting."
 
-    find_related_post_with_key: "Only use the reply key to find the replied-to post. (Recommended if using Amazon SES)"
+    find_related_post_with_key: "Only use the 'reply key' to find the replied-to post. WARNING: disabling this allows user impersonation based on email address."
 
     minimum_topics_similar: "How many topics need to exist before similar topics are presented when composing new topics."
 
diff --git a/config/site_settings.yml b/config/site_settings.yml
index 4e0dbdc5caa..ed2147124e3 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -633,7 +633,7 @@ email:
     default: ''
     validator: "AlternativeReplyByEmailAddressesValidator"
   find_related_post_with_key:
-    default: false
+    default: true
   manual_polling_enabled:
     default: false
   pop3_polling_enabled:
diff --git a/spec/components/email/receiver_spec.rb b/spec/components/email/receiver_spec.rb
index f84b15e169d..a7911a44465 100644
--- a/spec/components/email/receiver_spec.rb
+++ b/spec/components/email/receiver_spec.rb
@@ -400,7 +400,9 @@ describe Email::Receiver do
       expect(Topic.last.ordered_posts[-1].post_type).to eq(Post.types[:moderator_action])
     end
 
-    it "associates email replies using both 'In-Reply-To' and 'References' headers" do
+    it "associates email replies using both 'In-Reply-To' and 'References' headers when 'find_related_post_with_key' is disabled" do
+      SiteSetting.find_related_post_with_key = false
+
       expect { process(:email_reply_1) }.to change(Topic, :count)
 
       topic = Topic.last