AutoLogin is a free HostBill plugin that allows you to log-in your customers from external application/website with email address.

Added in 2016-05-06 release. The power of AutoLogin feature is that you are not forced to redirect user anywhere after log-in into your application, all actions are taken in background, between your application’s server and HostBill’s.
Additionally you can auto-logout customers once they will log-out of your application.

Connecting your application and auto-login should work with this flow:

1. Client logs-in into your application
2. Your application generates access hash from user email + secret from module configuration
3. Your application HTTP POST this hash to Auto-Login module
4. Module authenticates customer, and returns url that you should link your application from. I.e.: via “Access billing portal” link
5. Once customer visits this link he will be automatically logged in.
6. [Optional] When customer logs out of your application, it POST request to log-out customer from HostBill too.

Documentation/Code samples: https://hostbill.atlassian.net/wiki/display/DOCS/Auto+Login