By the end of 2009 the Mailing Preference Service suppression file contained just over 4.5 million entries, according to the Direct marketing material waste prevention report (DMA / Royal Mail, 2010). If we assume that each registration represents a single individual we can calculate that 9% of the adult population is currently registered with the opt-out scheme.

A problem with the figure is that some of the registrations may be households rather than individuals. Until September 2007 the Mailing Preference Service registered households, and so the list is currently a mix of households and individuals. It's unknown whether or not the figure of 4.5 million has been corrected to reflect the fact the opt-out scheme currently registers individuals only. Direct Marketing Association never reveals how they arrive at figures - even Defra isn't given an insight in its junk research. I image they will have corrected the figure; it's in the Direct Marketing Association's interest to make opt-out rates look impressive.

The Direct Marketing Association may have forgotten to account for the fact that individuals can register with the Mailing Preference Service more than ones. If I register the names 'Joe Bloggs', 'Joe F Bloggs' and 'Joseph Bloggs' I got three entries on the file, even though I'm only one person. Similarly, the list is likely to contain a lot of dead people; many people register the names of deceased loved ones in an attempt to stop junk mail addressed to them.

For many years Royal Mail refused to say how many households are registered with its opt-out scheme for unaddressed mail delivered by the postman (the Door-to-Door Opt-Out). Some people even submitted Freedom of Information requests to find out, but these were rejected because the information was deemed commercially sensitive. Stupidly, in 2008 the manager of the opt-out scheme told me in an e-mail that at the time “less than 0.5%” of households was registered with the scheme. Since Royal Mail has been less secretive; in the above-mentioned waste prevention report it was confirmed that in 198,000 households were registered in April 2009. That's just under 0.8% of all households.

The difference in registrations between the Mailing Preference Service and Door-to-Door Opt-Out is interesting. You'd expect the Door-to-Door Opt-Out to be the most popular scheme; it stops a greater volume of junk mail. The fact that so few households are registered is the result of Royal Mail's failure to advertise the existence of the scheme, the complicated opt-out procedure, and the scare tactics used by the company to discourage people from registering. For instance, Royal Mail has confirmed that about half the households requesting an opt-out form do not return it - presumably because they're worried about missing “important information”.

Opt-out rates for the Door-to-Door Opt-Out may be low, they're quite acceptable compared with the rates achieved by the Direct Marketing Association's opt-out scheme for unaddressed junk mail; the Your Choice scheme. Just how obscure, complicated, ineffective and customer-unfriendly this 'service' is can be illustrated by the fact that at the time of writing (July 2011) the scheme isn't advertised at all by the Direct Marketing Association. Hence, we need three decimal places to be able to show the opt-out rate:

Worth noting is that up to the end of 2009 exactly 4,501 people requested the Your Choice opt-out pack via Junk Buster. Even if we assume that all requests for the opt-out pack are made via Junk Buster (which is obviously nonsense) the percentage of householders deciding not to register after all is 65%. If we assume half of all opt-out packs are requested via Junk Buster the percentage is more than 80%. Unsurprisingly, the Direct Marketing Association omitted these details from its waste prevention report for Defra. (And, of course, Defra isn't questioning the figures it's being fed.)