API-Key credentials per domainname

Problem API keys are currently not "scoped" on the domains you create them for, meaning: if you know which other domains are validated in our account, you can use email spoofing. Feature Request It would be a great addition if API-Keys could be configured to be valid for certain domains only. Solution Suggestions By default: API keys should be valid for all domains. On the "edit API key" page provide a function that allows for the enabling of the granular permissions. After the feature has been enabled the user can select one or multiple domains.