The IP Reverse Lookup can return multiple domains for an IP.
There is also a query to check if an email is free or not.
A free API account is available, but after 250 requests it runs into a pumpkin and you must get a paid account.
viewdns.info/
There is also a query to check if an email is free or not.
A free API account is available, but after 250 requests it runs into a pumpkin and you must get a paid account.
viewdns.info/