OP_Expire and Coinbase-Like Behavior: Making HTLCs Safer by Letting Transactions Expire Safely

The email suggests using "nExpiryHeight" instead of a time-based approach for expiration in order to avoid potential issues with miners manipulating the current time. The suggestion is to redefine an OP_SuccessX opcode, eliminating the need for _Verify behavior and allowing for either OP_Expire or OP_CheckExpiryTime as better names for the opcode. The sender also acknowledges proposing an explicit field but realizes that the taproot annex makes it unnecessary. Additionally, having an nExpiryHeight could be beneficial in cases where a signature covering the field is sufficient.

Please note that the farewell part of the email has been excluded from this summary.