README.md in rumble-0.4.1 vs README.md in rumble-0.5.0

@@ -43,9 +43,11 @@
 ```
 
 The list of emails must contain three columns separated by a comma: first
 name, last name, and email.
 
+If you want to send via HTTP/SMTP proxy, use `--proxy=host:port`.
+
 # How to contribute
 
 Read [these guidelines](https://www.yegor256.com/2014/04/15/github-guidelines.html).
 Make sure you build is green before you contribute
 your pull request. You will need to have [Ruby](https://www.ruby-lang.org/en/) 2.3+ and