Why post a letter when an email is free?

The answer that does not need a statistic

For this trade the choice is not between a letter and an email. A council's planning register publishes the applicant's name and the address of the site. It does not publish an email address, and there is nowhere to go and get one.

Even if there were, the consent rule for unsolicited marketing covers email, texts and calls: you would need the applicant to have agreed first, and somebody who has just filed a planning application has agreed to nothing. A letter needs no such agreement — the rules it does have to meet are on their own page.

So post is not the better of two channels here. It is the one that exists.

What is measured about mail

Mail is measured by JICMAIL, the joint industry committee that runs a continuous panel of UK households. Royal Mail's marketing arm, Marketreach, publishes figures too — and it sells mail, so every one of its numbers below carries the credit it gives for it.

Direct mail prompts a physical interaction — 96%

Picked up, opened, put on a worktop, moved, kept — measured on a continuous panel of UK households rather than asked about in a survey. JICMAIL, read 20 October 2026.

Mail is engaged with — 95%

The same measurement from the other direction, and the two bodies agree to within a point. Royal Mail Marketreach, read 20 October 2026, credited by Marketreach to JICMAIL.

People describe mail as believable — 87%

Trust is the one place a letter has an argument an email cannot make: a letter cannot be a phishing attempt that costs the reader money. Royal Mail Marketreach, read 20 October 2026, credited by Marketreach to Marketreach, Trinity McQueen, Customer Mail.

Campaigns with mail in the mix report better returns — 52%

More likely to report a return benefit than campaigns without mail. It is about mixed campaigns rather than about mail on its own. Royal Mail Marketreach, read 20 October 2026, credited by Marketreach to Driving Effectiveness with Direct Mail, WARC.

Attention a Business Mail item gets, per month — 197 seconds

Business Mail is bills, statements and notices rather than marketing, so it is the wrong category for a builder's letter. It is here because it is the only attention figure either body publishes openly. JICMAIL, read 20 October 2026.

What nobody publishes

The comparison you will have seen — mail read by this many, email by that many — is not something either of those bodies puts on a page you can check. Figures of that shape circulate widely and the sources quoted for them do not carry them.

That cuts both ways and it is worth saying which way. It does not mean email performs better than the circulating numbers suggest. It means that if somebody shows you a tidy two-column table of mail against email, ask them which document it is in.

The one comparison that does stand up

JICMAIL's Response Rate Tracker measures what advertisers themselves reported from real campaigns, and it is the figure our own does direct mail work page is built on. It publishes a benchmark for cold mail to people who are not already your customers, and a much higher one for mail to people who have bought from you before. Both are on that page with the release linked and the day we read it printed beside them, which is why they are not retyped here.

That is a benchmark for mail against itself rather than against email, which is the honest shape of the evidence that exists.

What it costs to find out

The argument for a letter is not that it beats a free email on percentages. It is that the cost is small, known in advance, and aimed at somebody who has just told the council in writing that they intend to build something.

One job in a year covers that several times over. The sum, at every volume, is on what planning leads cost.

Where this page would be wrong

If a council register ever published applicants' email addresses, and if the people on it had agreed to be emailed, the argument at the top of this page would stop working and the one underneath it would have to carry the whole weight. Neither of those is true today.