Iro is a non blocking server for sending a message to a bunsh of recipient. It can handle diffrent types of message typs and can be extended easially. It was initially written for sms backend of castorticker.de. Diffrent backends are supportes by Iro.
A backend is a provider, that actually sends the message.
Just download ${code} see also installtion instruction under Installing Iro.
If you want just use iro see API Documentation. For extending iro see the developer documenation.