Is it legal to email past customers in the UK? The soft opt-in explained

[Simon Weiner]

This comes up constantly with local business owners sitting on a customer list they're afraid to use, so here is the full picture.

Short answer: yes, under specific conditions known as the PECR Regulation 22 "soft opt-in". You can email your existing customers marketing messages without fresh consent when ALL THREE of these hold:

1. The address was collected during a sale or negotiations for a sale (a genuine commercial relationship, not a scraped list or a networking card).

2. You are marketing your own similar products or services (a heating firm can promote boiler servicing to boiler customers; it cannot suddenly promote an unrelated product line).

3. Every email contains a clear, working opt-out — and you honour it.

Where businesses go wrong in practice:

The biggest failure is the MIXED LIST — genuine past customers blended in one spreadsheet with old enquiries who never bought, trade contacts, and addresses of unknown origin. That blend does not qualify wholesale: the soft opt-in covers customers, not browsers. Separate the buyers out before any send, and document the legal basis in writing (when collected, how, why it qualifies) dated before the campaign. If a complaint ever lands, that document is the difference between a non-event and a problem.

Second trap: regulated sectors carry their own marketing rules ON TOP of PECR. Dental practices answer to GDC marketing principles (no outcome claims), solicitors to the SRA, mortgage brokers to FCA financial-promotion rules, aesthetic clinics to ASA/CAP (no prescription-only medicine names in promotions). The soft opt-in covers the sending; the sector rules govern what the email may say.

Third: B2B vs B2C nuance. Emails to limited-company addresses sit outside the individual-subscriber rules, but sole traders and partnerships count as individuals in the UK — a trades supplier emailing sole-trader plumbers needs the same care as a dentist emailing patients.

Done properly, a structured reactivation campaign to a clean list of genuine past customers is both compliant and remarkably effective — the trust is already earned and the database already paid for. I have written up the full structure (the 7-email week, the deadline mechanics, costs) here: https://sites.google.com/view/customer-revival-campaigns-uk — and the long-form guide: https://www.linkedin.com/pulse/what-customer-revival-campaign-how-does-work-simon-iitrf/

Happy to answer questions on specific list situations.

Simon Weiner FCCA FCMA · AS Consulting · asconsulting.top