Which ESA function maintains a set of rules that control incoming connections from remote hosts for a listener?

LDAP is a directory query protocol used for recipient validation and group lookups, not for controlling incoming SMTP connections.

The HAT is a per-listener table on the Cisco ESA that maps remote host IP addresses or sender groups to specific mail flow policies, controlling connection-level behavior such as rate limiting, SMTP authentication requirements, and accept or reject decisions before a message is processed.

VEST is not a valid Cisco ESA component or feature name.

Sender groups are entries within the HAT that classify remote hosts, but the HAT itself is the overarching construct that maintains and applies the connection control rules.

The RAT (Recipient Access Table) controls which recipient addresses a listener will accept mail for, not the rules governing the connecting host itself.