Free email does not mean disposable

A signup form asks for a work email. Someone enters a Gmail address, and the application has to decide what to do with it. Identifying the mailbox provider is straightforward. Deciding whether that person is using the address for work is a different question.

The current Email API response has a free field for consumer mailbox domains. Gmail is one example. An address on a company's own domain returns free: false, even when the same mail service runs both inboxes. The field describes the domain used in the address, not what the person pays for their account or how they use it.

disposable answers whether the address uses a temporary or disposable email provider. That is separate from being a consumer mailbox. A person can keep a Gmail address for years, so free: true is not a reason to label an address temporary. These fields also don't answer whether a particular mailbox can receive mail.

It is tempting to turn free: false into a field called work_email. That would claim more than the result says. A personal domain can return false. A business contact can use a consumer mailbox. If your application needs someone's employer, ask for it instead of deriving it from this flag.

A domain category has the same boundary

domain_type identifies a recognized academic, government, or military namespace. For example, an address at mit.edu has this response excerpt:

{
  "domain": "mit.edu",
  "free": false,
  "domain_type": "academic"
}

That is useful context for a form or a contact record. It is not proof of current enrollment. The category belongs to the domain, and the response has no field saying whether the person is a student, a staff member, or an alumnus. Likewise, government and military describe the domain category without establishing the account holder's job or status.

The other result is null. Keep that as an unclassified domain, not a fourth category called business. It doesn't rule out an educational institution using a domain outside a recognized academic namespace. A name containing a word like "education" is not enough to establish the category either.

Both free and domain_type are included in the current basic Email response without requesting deep. The Email reference describes the separate mailbox checks. In your application, keep the domain facts under their own names and collect any facts you need about the person directly.