diff --git a/lib/lita/mailgun_dropped_rate_repository.rb b/lib/lita/mailgun_dropped_rate_repository.rb
index <HASH>..<HASH> 100644
--- a/lib/lita/mailgun_dropped_rate_repository.rb
+++ b/lib/lita/mailgun_dropped_rate_repository.rb
@@ -29,8 +29,8 @@ module Lita
       @mutex.synchronize do
         @store[domain] ||= []
         @store[domain] << event_name
-        if @store[domain].size > 100
-          @store[domain] = @store[domain].slice(-100, 100)
+        if @store[domain].size > 20
+          @store[domain] = @store[domain].slice(-20, 20)
         end
       end
       true
diff --git a/spec/mailgun_dropped_rate_repository_spec.rb b/spec/mailgun_dropped_rate_repository_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/mailgun_dropped_rate_repository_spec.rb
+++ b/spec/mailgun_dropped_rate_repository_spec.rb
@@ -31,9 +31,9 @@ describe Lita::MailgunDroppedRateRepository do
       end
     end
   end
-  context "when a single domain records 101 events" do
+  context "when a single domain records 21 events" do
     before do
-      101.times do
+      21.times do
         repository.record("example.com", :delivered)
       end
     end
@@ -49,7 +49,7 @@ describe Lita::MailgunDroppedRateRepository do
       end
 
       it "sets the total_count" do
-        expect(result.total).to eq(100)
+        expect(result.total).to eq(20)
       end
 
       it "includes the dropped rate" do
reduce history stored for each domain to <I> events

* <I> should be plenty to decide if there's an issue or not
* It's also low enough that low-volume domains that have an issue
  resolved should move into the green zone quicker