Install `mailcatcher` in development.

Gemfile

@@ -128,6 +128,7 @@ group :test, :development do
   gem 'pry-nav'
   gem 'byebug', require: ENV['RM_INFO'].nil?
   gem 'rubocop', require: false
+  gem 'mailcatcher', require: false
 end
 
 group :development do

Gemfile.lock

@@ -91,6 +91,7 @@ GEM
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.4)
+    daemons (1.2.6)
     danger (5.6.3)
       claide (~> 1.0)
       claide-plugins (>= 0.9.2)
@@ -126,6 +127,7 @@ GEM
       railties (>= 3.1)
     ember-source (2.13.3)
     erubi (1.7.1)
+    eventmachine (1.2.7)
     excon (0.62.0)
     execjs (2.7.0)
     exifr (1.3.4)
@@ -151,6 +153,9 @@ GEM
     globalid (0.4.1)
       activesupport (>= 4.2.0)
     guess_html_encoding (0.0.11)
+    haml (5.0.4)
+      temple (>= 0.8.0)
+      tilt
     hashdiff (0.3.7)
     hashie (3.5.7)
     highline (1.7.10)
@@ -168,6 +173,7 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
+    json (2.1.0)
     jwt (1.5.6)
     kgio (2.11.2)
     kramdown (1.17.0)
@@ -191,6 +197,16 @@ GEM
     lru_redux (1.1.0)
     mail (2.7.1.rc1)
       mini_mime (>= 0.1.1)
+    mailcatcher (0.2.4)
+      eventmachine
+      haml
+      i18n
+      json
+      mail
+      sinatra
+      skinny (>= 0.1.2)
+      sqlite3-ruby
+      thin
     memory_profiler (0.9.10)
     message_bus (2.1.5)
       rack (>= 1.1.3)
@@ -214,6 +230,7 @@ GEM
     multi_xml (0.6.0)
     multipart-post (2.0.0)
     mustache (1.0.5)
+    mustermann (1.0.3)
     nap (1.1.0)
     no_proxy_fix (0.1.2)
     nokogiri (1.8.3)
@@ -402,6 +419,14 @@ GEM
       connection_pool (~> 2.2, >= 2.2.0)
       rack-protection (>= 1.5.0)
       redis (>= 3.3.5, < 5)
+    sinatra (2.0.3)
+      mustermann (~> 1.0)
+      rack (~> 2.0)
+      rack-protection (= 2.0.3)
+      tilt (~> 2.0)
+    skinny (0.2.2)
+      eventmachine (~> 1.0)
+      thin
     slop (3.6.0)
     sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
@@ -410,10 +435,18 @@ GEM
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
+    sqlite3 (1.3.13)
+    sqlite3-ruby (1.3.3)
+      sqlite3 (>= 1.3.3)
     sshkey (1.9.0)
     stackprof (0.2.11)
+    temple (0.8.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
+    thin (1.7.2)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0, >= 1.0.4)
+      rack (>= 1, < 3)
     thor (0.19.4)
     thread_safe (0.3.6)
     tilt (2.0.8)
@@ -487,6 +520,7 @@ DEPENDENCIES
   logster
   lru_redux
   mail (= 2.7.1.rc1)
+  mailcatcher
   memory_profiler
   message_bus
   mini_mime