After installation BwPostman must be configured. To do so you click in the top right corner of Components → BwPostman at the button Options in the back-end of your Joomla!® installation. Or you click at the button Basic settings in the main view of BwPostman. The options are only available in the main view or in the maintenance.
The options are divided in seven sections: Basic Settings, Registration, Activation, Unsubscription, Lists View, Single View and Permissions. For all options there are tool-tips.
Since version 2.1.1 of BwPostman all texts of the options are multi-language-capable, where it makes sense. That means, You there may enter language strings and depose the appropriate texts at the override files for the respective language. Also see article Texts of Fields of BwPostman do not fit.