Creates a contact. This will also verify the contact's address if you create it using a live API key. To sucessfully create a contact, either a firstName, a companyName, or both are required. You can supply both, but you cannot supply neither.

You have the option to supply the entire address (except for countryCode) via addressLine1, in which case PostGrid will parse it automatically. However, this is not guaranteed to be correct, so we recommend passing along the structured address fields (city, provinceOrState, etc) if you have them.

Note that if you create a contact that has identical information to another contact, this will simply update the description of the existing contact and return it. This avoids creating duplicate contacts.