This Node.js tool regularly scrapes sites where flats are offered to buy.
Flatfinder makes use of the Mailgun API in order to send mails with new offers. You need to have an account in order to use this functionality. Your account data have to be passed in as environment variables:
mailgun_url // eg. https://api.mailgun.net/v3/yourdomain.mailgun.org/messages
mailgun_user // eg. api
mailgun_key // eg. key-asd213102ad
mailgun_to // eg. mrdeveloper@web.de