On the 18th of December 2008, our team installed the very first release of the sender based routing agent ExSBR at the first client. The client has been an IT provider with international customers in their multi-tenant environment. As some customers of our client had special requirements for their outbound emails, we decided to develop and install our own routing agent to solve the problem. This first release has been the foundation of ExSBR. The software itself had been developed new from scratch to be configurable and more performant than the initial release.