Subscribe an email address to a list. This api call has the same behavior as a regular subscribe form. However, single opt-in is allowed for system integration purposes.
- If email address does not exist, a new contact will be added to the list.
- If email address exists custom fields will be updated and status will be put to unconfirmed or active depending of singleoptin value.
- If current status if Active, this operation will only update the custom fields.
- If singleoptin is true, no email confirmation will be sent. In that case, you must provide the subscribe's origin ip and confirmation date-time.