diff --git a/app/controllers/api/submitter_email_clicks_controller.rb b/app/controllers/api/submitter_email_clicks_controller.rb
index 87221680..7d6461f8 100644
--- a/app/controllers/api/submitter_email_clicks_controller.rb
+++ b/app/controllers/api/submitter_email_clicks_controller.rb
@@ -8,7 +8,8 @@ module Api
     def create
       submitter = Submitter.find_by!(slug: params[:submitter_slug])
 
-      if params[:t] == SubmissionEvents.build_tracking_param(submitter, 'click_email')
+      if params[:t] == SubmissionEvents.build_tracking_param(submitter, 'click_email') ||
+         params[:t] == SubmissionEvents.build_tracking_param_legacy(submitter, 'click_email')
         SubmissionEvents.create_with_tracking_data(submitter, 'click_email', request)
       end
 
diff --git a/lib/submission_events.rb b/lib/submission_events.rb
index e0b9c70b..41addfbf 100644
--- a/lib/submission_events.rb
+++ b/lib/submission_events.rb
@@ -20,9 +20,15 @@ module SubmissionEvents
 
   module_function
 
+  def build_tracking_param_legacy(submitter, event_type = 'click_email')
+    Base64.urlsafe_encode64(
+      [submitter.slug, event_type].join(':')
+    ).first(TRACKING_PARAM_LENGTH)
+  end
+
   def build_tracking_param(submitter, event_type = 'click_email')
     Base64.urlsafe_encode64(
-      [submitter.slug, event_type, Rails.application.secret_key_base].join(':')
+      Digest::SHA1.digest([submitter.slug, event_type, Rails.application.secret_key_base].join(':'))
     ).first(TRACKING_PARAM_LENGTH)
   end