1 files changed, 36 insertions, 0 deletions
diff --git a/lib/gitlab/mailgun/webhook_processors/failure_logger.rb b/lib/gitlab/mailgun/webhook_processors/failure_logger.rb
new file mode 100644
index 00000000000..a7a85bd1672
--- /dev/null
+++ b/lib/gitlab/mailgun/webhook_processors/failure_logger.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Mailgun
+    module WebhookProcessors
+      class FailureLogger < Base
+        def execute
+          log_failure if permanent_failure? || temporary_failure_over_threshold?
+        end
+
+        def permanent_failure?
+          payload['event'] == 'failed' && payload['severity'] == 'permanent'
+        end
+
+        def temporary_failure_over_threshold?
+          payload['event'] == 'failed' && payload['severity'] == 'temporary' &&
+            Gitlab::ApplicationRateLimiter.throttled?(:temporary_email_failure, scope: payload['recipient'])
+        end
+
+        private
+
+        def log_failure
+          Gitlab::ErrorTracking::Logger.error(
+            event: 'email_delivery_failure',
+            mailgun_event_id: payload['id'],
+            recipient: payload['recipient'],
+            failure_type: payload['severity'],
+            failure_reason: payload['reason'],
+            failure_code: payload.dig('delivery-status', 'code'),
+            failure_message: payload.dig('delivery-status', 'message')
+          )
+        end
+      end
+    end
+  end
+end