I like to use Sendiio as an effective autoresponder.
If any possibility Sendiio support email is ([email protected]). You are free to liaise with them for a solution if possible.
To get the integration with Sendiio, their API documentation page link is (https://sendiio.com/pages/view/sendiio-api)
at this point, all I'm doing is asking possible integration.
Please let me know if this would be possible or not???