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Online Advertising

Building a list without buying one

Bought addresses are unlawful in most European markets and commercially worthless. The slow route through your own sign-ups is the only one that holds.

May 31, 2026 2 min read 394 words
Building a list without buying one

Key points

  • Without documented consent every commercial send is a breach.
  • A good incentive converts 3 to 8 per cent of visitors; a poor one 0.2.
  • Reckon on 18 to 36 months before a list carries commercially.

The wish for a large list quickly leads to two mistakes: bought addresses and silently harvested contacts. Both are unlawful and practically worthless.

Commercial email to individuals requires prior express consent. That consent must be logged, with the time, the wording shown and evidence of confirmation.

There is a narrow exception for existing customers: someone who has bought from you may be advertised similar goods of your own if, when the address was collected and in every message, the right to object was pointed out. That exception is narrow and does not cover third-party offers.

A bought list costs twice: once at purchase and once at the legal complaint. In between it delivers open rates under five per cent and ruins your domain's deliverability.

Double confirmation is compulsory

After sign-up the person receives a message with a confirmation link. Only the click makes them a recipient. Without that procedure you cannot prove in a dispute that the sign-up came from the person themselves.

Store per sign-up: timestamp, IP address, the consent wording displayed, and the confirmation timestamp. Those four entries are the whole proof.

Incentives that actually work

A newsletter alone is not an incentive. The visitor's question is: what do I get?

IncentiveSign-up rateAddress quality
Discount voucher4 to 9 %low, often one-time buyers
Checklist or template3 to 7 %high, topically matched
Price list or calculator5 to 12 %very high for services
Sample despatch2 to 5 %very high
Plain newsletter sign-up0.2 to 0.8 %medium
Prize draw10 to 25 %very low

The last row is the trap. Prize draws fill lists fast with people who wanted the prize. Those addresses do not open, do not click and drag deliverability down.

Where to place the sign-up

  1. At the end of every article, matched to the topic.
  2. In the order confirmation, as an unticked box.
  3. As an exit-intent prompt, sparingly and not on phones.
  4. In every colleague's signature.
  5. On invoices and delivery notes, with a short link.
  6. After the contact form, as a second step.

Points four and five cost nothing and are almost always forgotten.

The realistic timetable

A mid-sized firm with 2,000 site visits a month and a 3 per cent sign-up rate gains 60 addresses monthly, around 50 net of unsubscribes. After a year that is 600; after two years 1,200.

That sounds slow, and it is the reason to start today rather than when you need the list.

Frequently asked questions

Can business cards from a trade fair go into the list?

Only if the person expressly agreed to the newsletter. Handing over a card is making contact, not granting advertising consent.

How many addresses before it is worth it?

With an order value above £2,000, 300 active addresses already pay. In retail the threshold is nearer 3,000.

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