Symptoms
Customer has several webspaces on his subscription.
Trying to add >500 domains on the subscription through OpenAPI results in the error:
Max websites per webspace limit (500) exceeded for webspace
Cause
There is no possibility to indicate the webspace ID in pem.addDomain call.
500 is the hardcoded limit of websites per webspace.
Resolution
Use GUI tools in order to add more than 500 domains on subscription.