Overview
Lookup lists serve a similar role to in-memory stores such as Redis, but with one key distinction: they are read-only at runtime. They hold key-value pairs that remain unchanged during server operation and are well suited to cases where a fixed set of values is consulted from configuration expressions or scripts.
Local
Local lookup lists hold key-only membership sets and key-value pairs entirely in memory. They are well suited to small, slow-changing sets of static data, consulted from expressions or Sieve filters.
Remote
Remote lookup lists retrieve key-value pairs from an external source over HTTP, allowing lookup data to be managed centrally and refreshed periodically. Two formats are supported: a simple list format where each entry occupies a single line, and CSV for more structured data.