diff --git a/app/models/reviewable_user.rb b/app/models/reviewable_user.rb
index 85f8903357a..299fd648686 100644
--- a/app/models/reviewable_user.rb
+++ b/app/models/reviewable_user.rb
@@ -46,6 +46,9 @@ class ReviewableUser < Reviewable
       begin
         self.reject_reason = args[:reject_reason]
 
+        # Without this, we end up sending the email even if this reject_reason is too long.
+        self.validate!
+
         if args[:send_email] && SiteSetting.must_approve_users?
           # Execute job instead of enqueue because user has to exists to send email
           Jobs::CriticalUserEmail.new.execute(
diff --git a/spec/requests/reviewables_controller_spec.rb b/spec/requests/reviewables_controller_spec.rb
index 4fcb0280a37..26b7e9f23f7 100644
--- a/spec/requests/reviewables_controller_spec.rb
+++ b/spec/requests/reviewables_controller_spec.rb
@@ -187,7 +187,7 @@ RSpec.describe ReviewablesController do
         expect(json["errors"][0]).to eq(I18n.t("reviewables.already_handled_and_user_not_exist"))
       end
 
-      it "returns a readable error message if reject_reason is too long" do
+      it "returns a readable error message if reject_reason is too long, does not send email, and does not delete the user" do
         sign_in(admin)
         Jobs.run_immediately!
         SiteSetting.must_approve_users = true
@@ -195,11 +195,14 @@ RSpec.describe ReviewablesController do
         user.activate
         reviewable = ReviewableUser.find_by(target: user)
 
-        put "/review/#{reviewable.id}/perform/delete_user.json?version=0",
-            params: {
-              send_email: true,
-              reject_reason: "a" * 3000,
-            }
+        expect {
+          put "/review/#{reviewable.id}/perform/delete_user.json?version=0",
+              params: {
+                send_email: true,
+                reject_reason: "a" * 3000,
+              }
+        }.to not_change { ActionMailer::Base.deliveries.size }.and not_change { User.count }
+
         expect(response.code).to eq("422")
         expect(response.parsed_body["errors"]).to eq(
           ["Reject reason " + I18n.t("errors.messages.too_long", count: 2000)],