Paying For Interchain Gas

Changes have been made to how gas payments work and a new set of IGP contract addresses have been released as of January 25, 2023. The latest information is reflected here. See Migration to Enforced Interchain Gas Payments for migration details and future plans.
The lifecycle of a Hyperlane message involves two transactions: one on the origin chain to send the message, and one on the destination chain to deliver the message.
For convenience, Hyperlane provides an on-chain API on the origin chain that can be used to pay relayers in the origin chain's native token to deliver messages on the destination chain. This payment is called an interchain gas payment.