Delivery evidence is proof that a message was sent and received within a controlled messaging system. In practice, it can include delivery receipts, timestamps, sender and recipient identifiers, message hashes, and signed logs that show when the system accepted and routed the message.
In cyber security, delivery evidence matters because it supports auditability, dispute resolution, and non-repudiation. It helps defenders prove that a notice, request, or instruction passed through an approved channel, which is important in regulated communications. Attackers may try to forge receipts, delete logs, replay messages, or hijack an account to create false evidence. Strong protections such as access control, multi-factor authentication, cryptographic signing, and immutable logging help preserve the trustworthiness of the record.