I'm attempting to create a new contact in CC that hasn't yet been assigned to any particular list. Since existing emails that are removed from all lists go to the "removed" list, it stands to reason that I should be able to place an email there directly.
<ContactList xmlns="http://ws.constantcontact.com/ns/1.0/" id="https://api.constantcontact.com/ws/customers/cascadedsdev/lists/removed"/>
The message I get back is that "removed" is an invalid list. I'm guessing that what I'm trying to do isn't possible but thought I would ask anyway in the off chance that I'm simply doing it incorrectly.
Unfortunately, the exact flow you are looking for would not quite work in Constant Contact. 'Removed' is a system list that contacts cannot be directly added to by supplying the list id in the contacts <ContactList> element, and the same is true for 'Active' and 'Do Not Mail'. Being on the 'Removed' list is really an indication of the absence of any real 'lists', and therefore is giving you the correct message that 'removed' is not valid. We also do not have the ability to add a contact without specifying an exact list for them to be on, so specifying no list is not an option either.
I think you're going to have a cleaner integration with waiting to add the contact to your account until you are ready for them to be part of an active list, but the other way to accomplish this would be to add the contact, and then update them removing all contact lists. You can more information on this in Removing a Contact.
I hope this helps. Please let us know if you have any other questions. Thanks.