The database was established by the Stop Dead Consortium, which includes organisations such as Age Concern, Help the Aged, Liverpool Victoria and Readers' Digest.
The organisations worked together to help pool names of people who have died. This can be used by fundraisers and the direct marketing industry to help avoid causing distress to the relatives of dead people by sending them mail.
The consortium said that September's file would be even larger as existing members give their first data supply and potential new members sign up for the service.
Emma Reid, joint founder of the project, said: "Commercial files have proved their effectiveness over the past few years. By working on a not-for-profit basis, OBiT has enabled its founder members to justify the release of data which is not currently commercially available.
"Additionally, the lower cost of OBiT data will encourage businesses not currently using suppression data, particularly in the charities world, to enter the market."
The Stop Dead Consortium continues actively to recruit businesses for contribution to OBiT.
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