Merge pull request #21174 from melissawahnish/document_gmail

[ci skip] Adding a note to Action Mailer Basics documentation that Google increased its security measures

guides/source/action_mailer_basics.md

@@ -759,6 +759,9 @@ config.action_mailer.smtp_settings = {
   authentication:       'plain',
   enable_starttls_auto: true  }
 ```
+Note: As of July 15, 2014, Google increased [its security measures](https://support.google.com/accounts/answer/6010255) and now blocks attempts from apps it deems less secure.
+You can change your gmail settings [here](https://www.google.com/settings/security/lesssecureapps) to allow the attempts or 
+use another ESP to send email by replacing 'smpt.gmail.com' above with the address of your provider.
 
 Mailer Testing
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