Google recently announced creating a new client account within an MCC. For AdWords users that rely on an MCC account to access their clients, this provides a more secure, scalable experience. However, API developers will need to consider how this impacts the way they access and manage accounts in their custom applications.
"All AdWords accounts will continue to have a unique numerical customer ID, as well as a "descriptive name" field. Any account that already has a login email will continue to function normally, and you can invite a new unique login email to any account (regardless of how it was created) if necessary. In short, the safest thing is to make sure your app doesn't assume the existence of a login email for any client accounts that you manage via MCC."
Here're some ways that your API app might rely on login emails:
- If you use login emails as unique identifiers in your database or UI
- If you use "clientEmail" header instead of the "clientCustomerId" header
- If you request Auth tokens at the client level as opposed to MCC level
- If you filter calls to InfoService by login email; it doesn't yet support filtering by customer ID
- If you use v13's AccountService.getClientAccounts() call, which returns an array of login emails, you should explore switching to v201101's ServicedAccountService.get() call, which includes the customer ID in the return value.
[Source: AdWords API blog]