MailEnable WebMail can be configured to allow access via Facebook login. It requires configuring settings within Facebook and then entering an Application ID and Application secret into MailEnable.

Once you have configured the Facebook settings within MailEnable, the webmail login screen will then show a Facebook login button. 

When the user clicks the login button, it will initially ask to confirm MailEnable login details and then pair the account with the user's Facebook login. 

From then onwards, the user can access eheir mail by clicking the Facebook login button, without having to enter their username and password.

Before you can allow Facebook logins to your web site (including webmail), you must register your site with Facebook.

The following link outlines how to configure this within Facebook:

https://developers.facebook.com/docs/apps/register

You typically need to configure a separate application for each domain that is hosted on your server (or at least each domain that is used to access webmail).

For example, if all your users access webmail via a single host name/URL then you need only to register that host name with Facebook.

If you host many domains/organizations, then you will need to register each domain as a separate Facebook application.

Once you have configured the Facebook application for the domain, you should ensure that each of the domains have a host header defined under webmail. You should ensure that the default postoffice for the header is set to the respective postoffice/domain.

If you have only a single domain providing webmail, you can define the same Application ID and Secret for the entire server. This can be configured under via Server/localhost properties.

If you have multiple host names providing webmail, you will need to configure Facebook integration for each postoffice/organization.

If you do this, you will need to also ensure that a host header is created for webmail.

The host header entry should be associated with the postoffice you with the defined Application ID and Application Secret (which is configured under the properties of the postoffice).

When a user accesses webmail, they will notice a Facebook Login button. When they first click this button, they will be asked to pair login to the Facebook application.

Once they have done this, the user will then be asked to enter their MailEnable credentials so the two accounts can be linked.

From that point onwards, the user can login to their webmail without challenge (assuming they have logged into Facebook).

The user can remove the application and configure access levels for Facebook integration under their user settings (just as they can with any other application).

If the user wishes to disassociate their Facebook login from their MailEnable login, they can login to webmail and remove the connection under the Settings/Login menu.

If they then click the login with Facebook option on the login screen, they will be challenged for their MailEnable credentials so as to authorize the use of Facebook to login.

If the user clicks the "Connect" button, it will reconnect their MailEnable account with Facebook without prompting for credentials (because they are already logged in).