The use of open, Internet-based communications for business-to-business (B2B) interactions requires accountability for and acknowledgment of the actions of participants. Accountability and acknowledgment can be achieved by the systematic maintenance of an irrefutable audit trail to render the interaction non-repudiable. To safeguard the interests of each party, the mechanisms used to meet this requirement should ensure fairness. That is, misbehaviour should not disadvantage well-behaved parties. Despite the fact that Web services are increasingly used to enable B2B interactions, there is currently no systematic support to deliver such guarantees. This paper introduces a flexible framework to support fair non-repudiable B2B interactions based on a trusted delivery agent. A Web services implementation is presented. The role of the delivery agent can be adapted to different end user capabilities and to meet different application requirements.