An OSINT collection utility which gathers information about domains. Hunts for subdomains, searches SHODAN for hits, grabs banners and headers, web UI. Don't know if there's an API yet.
How to set up MX records for subdomains (subdomain.foobar.com) that are separate from the primary domain and are authoritative when you are a Dreamhost customer. In other words, this is how you set up your Dreamhost configs such that you can send e-mail to subdomain.foobar.com and have it go to a separate mail server or provider from that for foobar.com.