Google Apps for business is a set of Google services for companies including email,
online storage, calendars, etc. This allows companies to avoid the hassle of having to manage all these services in house and simply outsource it. One of those services is email. A company can have their personal email domain but still working under the gmail platform.
I realized that when I enter a valid email address from a company using Google Apps, the response code is 302 with the location header containing an internal url. As you may know, 302 is used to indicate
the browser that the resource is in a different place, specifically where the location header points to. Read more