README.md in mailkick-0.4.0 vs README.md in mailkick-0.4.1

@@ -121,9 +121,17 @@
 gem 'mailgun-ruby'
 ```
 
 Be sure `ENV["MAILGUN_API_KEY"]` is set.
 
+#### Postmark
+
+```ruby
+gem 'postmark'
+```
+
+Be sure `ENV["POSTMARK_API_KEY"]` is set.
+
 #### Other
 
 Will gladly accept pull requests.
 
 ### Advanced