diff --git a/Gemfile.lock b/Gemfile.lock
index b4d4a6bb6..9e76ebda4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -234,7 +234,7 @@ GEM
       railties (>= 3.2)
     loofah (2.0.3)
       nokogiri (>= 1.5.9)
-    mail (2.6.5)
+    mail (2.6.6.rc1)
       mime-types (>= 1.16, < 4)
     mime-types (3.1)
       mime-types-data (~> 3.2015)