subscriber addresses are stored hashed for faster access.
Ezmlm interactions are done by sending messages to specific command addresses, rather than by placing commands in the Subject: line or message body. To subscribe to "mylist@host.org", mail "mylist-subscribe@host.org".
All changes of subscriber status are securely verified. Upon receipt of your request, ezmlm sends back a confirmation request with a cryptographic cookie in the Reply-To: address. This assures that the request was from you. Simply reply and you are a subscriber.
Users cannot get access to a subscriber list to prevent spammers from using lists to collect addresses. Optionally, subscriber address lists can be made available to the list owner.