diff --git a/Gemfile.lock b/Gemfile.lock
index dd74eba..3460ea8 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,11 +3,9 @@ GEM
   specs:
     httpclient (2.8.3)
     json (2.3.0)
-    mail (2.6.6)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.1)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0521)
+    mail (2.7.1)
+      mini_mime (>= 0.1.1)
+    mini_mime (1.0.2)
     nationbuilder-rb (1.6.2)
       httpclient (~> 2.7)
     slack-notifier (2.3.1)