A mailing list for your online store: how to collect email addresses legally

Updated: 11 November 2026

Visitors who come once and leave without buying are usually gone for good. If you get their email address, you can remind them of your store when it matters, for example during a sale or before Christmas. Here is how to build a mailing list.

First, the rules

In Poland you need the recipient's prior consent to send commercial information by email, also if they are already your customer. This follows from electronic communications law and the GDPR. Consent must be freely given, specific and easy to withdraw.

In practice: don't pre-tick the marketing box, say what people sign up for, record when and how they consented, and include an unsubscribe link in every email.

1. A discount for an email address

A popup offering, say, 10% off the first order in exchange for an email address is the most common approach. Show it after a few seconds or when the visitor is about to leave, not the moment the page opens.

2. Back in stock alerts

When a product is sold out, the customer can leave their email and get a message when it's back. These are people with clear interest, and the email is a service they asked for.

3. At checkout

In Shopify's checkout, customers can tick a box to receive marketing emails. Make sure it isn't pre-ticked.

What to send

A welcome email right away, with the discount code if one was promised.
New products and offers, but not too often. Once or twice a month is a good start.
Reminders before big days: Black Friday, Christmas and Mother's Day.
Always an unsubscribe link.

Take care of the list

Email addresses are personal data. Use them only for the purpose people agreed to, and stop emailing anyone who unsubscribes right away.