Several proposals have recently been published for the signing of messages,primarily email messages, to deter source address spoofing. These include: DomainKeys, draft-delany-domainkeys-base-00.txt Identified Internet Mail, draft-fenton-identified-mail-00.txt E-mail Postmarks, http://www.lessspam.org/EmailPostmarks.pdf While the prevention of message spoofing is also a goal of the MARID working group, cryptographic approaches to this problem are explicitly outside the charter of MARID. Nevertheless, many that are familiar with the address-based authorization approaches MARID is considering consider them to be an interim step until message signing is deployed, or as a complementary technology to be used along with message signing. This BOF (and IETF Working Group formation, if there is sufficient interest) will focus on standards for message signing, including: - Signature format (syntax) and binding to message source dress - Key management procedures - Selection of message content to be signed (headers, etc.) - Mechanisms for minimizing breakage as messages pass through the mail system - Operation of message signing in concert with address-based authorization