Town Halls and Provincial Diputations that have the competence to issue and process trafic sanctions have until the 25th of May 2016 to incorporate into the TESTRA system of Trafico, the electronic notice board where all fines that could not be delivered by email or ordinary mail, or that not have received a satisfactory or timely response, are published.
You can check if your Town Hall is already connected, by clicking this link.
https://sede-cdn-org.dgt.gob.es/es/tramites-y-multas/alguna-multa/consulta-tablon-edictal-testra/organismos-emisores-testra.shtml
Update 31.5.2015 Periodically the newly connected Town Halls are published on the BOE State Boletin and this month e.g. the Patronato de Recaudación Provincial de Málaga and that of Salamanca are included on the list, thus adding a large amount of Town Halls in one go.