How to build a contact list for broadcasts — and stay legal
Buying a number list and blasting it with ads is fast, illegal, and ineffective. Here is where good contact lists actually come from, how to get proper consent, and what happens if you skip that step.
Why a purchased list is a bad idea
Contact databases are sold on various forums and marketplaces: "10,000 UK business owners", "car owners in London", and so on. The appeal is obvious — instant scale without effort. Here is what actually happens:
- People on bought lists have no idea who you are and did not ask to hear from you — spam complaint rates are high.
- Enough spam reports and WhatsApp will ban your number within hours.
- In the EU, sending unsolicited marketing without consent is a GDPR violation. Fines can reach €20 million or 4% of annual global turnover, whichever is higher.
- Purchased lists are often stale: numbers are inactive, people have switched carriers, the data is months or years old.
Where good contact lists come from
A good list is one you built yourself, where people gave explicit consent. These are the realistic sources:
1. Existing customers who have bought from you
Your most valuable audience. They already trust you. If they left their number at checkout and ticked a box agreeing to updates, that is a legally sound, high-converting list. Response rates are consistently higher than any cold outreach.
2. Lead magnets and opt-in forms
Offer something of genuine value in exchange for a number: a first-purchase discount, a useful PDF, a free consultation. The form must include an explicit, unticked opt-in checkbox — something like "I agree to receive updates via WhatsApp". Pre-ticked does not count.
3. Telegram subscription bot
A simple bot with a /start command that explains what the person is signing up for, then offers a "Subscribe" button. Consent is explicit and timestamped in the bot logs. See chatbot without a developer for how to set up this kind of flow without writing code.
4. QR code at the point of sale
For physical locations: a QR code on a receipt, counter card, or packaging leads to a subscription page or directly opens a chat. The customer initiates contact themselves — that is unambiguous consent.
5. Click-to-messenger advertising
Platforms including Meta and Telegram allow ads with a "Message on WhatsApp" or "Open in Telegram" button. A person who clicks through and initiates conversation has self-selected — a much warmer lead than a cold number.
How to document consent properly
Consent should be:
- Explicit — a checkbox, a button, a separate confirmation phrase.
- Informed — the person understands what they are agreeing to: "I agree to receive news and offers via WhatsApp."
- Recorded — store the timestamp, source (form URL, bot ID), and the exact consent text. This is your defence if a complaint is ever filed.
- Revocable — every broadcast should include clear opt-out instructions: "Reply STOP to unsubscribe" or a button.
Segmentation: why dividing your list matters
A segmented list of 500 people outperforms a random list of 5,000 every time. At minimum, split your contacts by:
- Status: new leads, active customers, lapsed customers.
- Interest: which product or service they enquired about or bought.
- Geography: if you have multiple locations or serve different regions.
- Engagement: who opened and replied to previous broadcasts.
In chat-valet, when you upload a contact list you can include custom variables — {name}, {city}, {product}. Personalised messages get read more often than generic ones.
Volume and frequency
Even with a fully consented list, more is not better. Most niches do fine with one or two broadcasts a month. Each one should deliver something genuinely useful: a promotion, a product update, an answer to a common question.
On the technical side, we recommend no more than 20–30 messages per day from a single number, with pauses between sends, and using spintax to vary message text. This reduces (but does not eliminate) the risk of a ban. See how many messages you can send on WhatsApp for the full picture.
From list to first broadcast
Once your list is ready and consent is documented, it is time to launch. In chat-valet you upload contacts as a CSV, add variables, set send delays and a daily schedule. The full mechanics are on the WhatsApp broadcast page.
Upload your contact list and send your first broadcast — try free for 30 days, no card required.
Start broadcastingFrequently asked questions
Do I need consent to send broadcast messages?
Yes. In most jurisdictions — including the EU (GDPR), UK, and many others — sending unsolicited marketing messages requires prior consent from the recipient. This applies to WhatsApp and Telegram the same way it applies to email or SMS.
What counts as valid consent?
An explicit action from the person: a ticked opt-in checkbox on a form, pressing a subscription button in a bot, or joining a group or channel whose description clearly states it is used for broadcasts. Pre-ticked boxes and implied consent do not hold up.
Can I buy a ready-made contact list?
Legally, no: those people have not consented to hear from you. In practice many businesses try it, but the outcome is predictable — high spam complaint rates, account bans, and potential regulatory fines. We only recommend lists you have built yourself.
How long can I keep contacts, and what do I do when someone unsubscribes?
Under GDPR and similar laws, personal data should not be kept longer than necessary for the stated purpose. When someone unsubscribes, stop messaging them and delete their data on request.
What do I do with customers already in my phone contacts?
Customers who have bought from you or initiated contact are a legitimate audience. Sending them relevant updates is reasonable — but honour any unsubscribe request immediately.
How often should I send broadcasts?
Even with a fully consented list, restraint matters. For most niches, one or two broadcasts a month is enough. Every message should deliver value — a promotion, new product, or genuinely useful update.