I'm trying to write an application that creates mail accounts for thousands of users using the Google Directory API. Creating them one by one works, but is extremely slow. I tried to use the batch requests which is suppose to support up to 1000 requests at once. However with that, only around 50 users are created successfully and the rest of the requests throw 403 errors. If I change the batch size to 40 instead, after the first batch, many requests fail with 5xx errors.
If the batch requests are still limited by the same rate limits, the seem to be worthless as I could just send those requests individually at that slow rate. Is there a better way to do this or is there something else I should do instead?