When you signed-up for a PolarisMail account, you chose a username & password for managing your account. This is the Administrator's Account that you use to login to:
This interface will let you manage your domains, users, aliases, lists, branding and domain wide preferences. Many settings overlap with User defined settings and in those cases, the User preferences will take over. For example, as an Administrator you can blacklist the domain "abcd.com" but if a user whitelists "email@example.com", the whitelist will take priority.
Click on the pages on the left in order to find out how to perform common Administration tasks.