These commands are only available to remote administrators. They need to be explicitly enabled, i.e. they are disabled by default, even for remote administrators. Anyone can send these commands, but they are allowed only if the recipient is a remote administrator. Thus, if ‘address@addhost’ sends a message to ‘firstname.lastname@example.org’, ezmlm will reply with a subscriber list to ‘mod@modhost’ if this address is a remote administrator, and if the list is configured for remote subscriber listing.