Didn't understand why the bundle neglected to integrate with SonataAdmin. Even went so far creating my own services and child controllers, little did i know there was a configuration option available!!
Anyhow, the documentation should probably be tweaked, to include;
You can also integrate the bundle into SonataAdmin:
# app/config/config.yml
lexik_mailer:
sonata_integration: true # enable integration (default is false)