If you are looking for technical "postmaster" info (like if you're a mail admin trying to fix delivery issues to @icloud.com addresses), Apple provides a Postmaster information page . You can contact their team at icloudadmin@apple.com for specific delivery problems.
Post-it - Приложение - App Store icloud
The phrase "post: icloud" could refer to a few different things depending on what you're trying to do. Here are the most likely interpretations: If you are looking for technical "postmaster" info