diff --git a/Gemfile b/Gemfile
index b4ddae0..fa58868 100644
--- a/Gemfile
+++ b/Gemfile
@@ -60,3 +60,4 @@ gem "bcrypt"
 gem 'roo'
 gem 'roo-xls'
 gem 'simple_form'
+gem 'midi-smtp-server', require: false