Buying a ready-made list of addresses, or pre-checking the "Subscribe to newsletter" box during checkout, still feels like an easy way to quickly get email marketing off the ground. In practice, though, these methods tank your deliverability metrics — and it's not just one specific campaign that can get caught in spam filters, but the entire company domain, for months at a time.
The era when you could mass-email people without their explicit consent is over for good. Modern email marketing runs on transparency, deliberate user choice, and a spotless technical reputation.
Why hidden methods hurt campaign performance
Email providers (Gmail, Yandex, Mail.ru) have fully switched to AI-based sender scoring. Now, protection systems look not just at technical signatures (SPF, DKIM, DMARC), but at real-time audience engagement.
If the algorithm sees that recipients are mass-ignoring emails, deleting them unread, or clicking "Report spam," the server instantly lowers your domain's trust score, routing all subsequent campaigns straight into spam.
Comparing list-building approaches and their impact on deliverability
Evaluation criterion | Purchased lists / hidden checkboxes | Ethical collection (double opt-in) |
|---|---|---|
Risk of hitting spam traps | High (up to 10–15% of the list) | Zero (technically ruled out) |
Average spam complaint rate | Above 0.3% (the domain-blocking threshold) | Below 0.02% (within a safe range) |
Open Rate and CTR | Low (OR under 5%, CTR under 0.3%) | High (OR 25–40%, CTR 3–8%) |
Domain reputation in postmaster tools | Drops to critical levels | Consistently high ("green zone") |
Economic impact (ROI) | Minimal, due to blocks | High, thanks to working with a warm list |
The main technical risks to sender reputation
With unethical collection methods, senders inevitably run into the following factors:
1. Triggering spam traps
Any purchased or scraped list contains trap addresses. These fall into two types:
- Pristine traps: addresses that never belonged to a real person. Email providers create these specifically to detect unauthorized mass mailing. An email to one of these is an automatic signal to the system that the list was collected illegally.
- Recycled traps: old mailboxes of real users that were abandoned and then converted by the provider into traps. Having addresses like this on your list signals that the company doesn't maintain proper list hygiene.
2. Hidden checkboxes and user reaction
When a user finds an email in their inbox from a company they never knowingly agreed to hear from (because the opt-in checkbox was hidden in fine print at the bottom of the checkout page), the first natural reaction is irritation. Major providers enforce a hard spam-complaint limit of 0.1–0.3%. Just 3 clicks of the "Spam" button per 1,000 emails, and the whole company's deliverability plummets.
Conclusion: A hidden opt-in only creates a short-term illusion of list growth, one that ends up costing you an important sales channel down the line.
How to build an ethical list without losing conversion
Switching to transparent communication methods doesn't mean your list stops growing. On the contrary, you start collecting an exclusively targeted, paying audience.
- Transparent double opt-in. A two-step confirmation is the gold standard in marketing. The user enters their email on the site, gets an automatic email, and confirms the subscription by clicking a link. This guarantees 100% protection from spam traps and typos.
- An honest exchange. Instead of hidden tricks, offer real value in exchange for subscribing: a useful guide, a checklist, a discount on the first order, or access to a private sale. Users should clearly understand they're giving up their email in exchange for something worthwhile.
- Managing frequency and topics. Give users a choice right in the signup form or their account settings: do they want daily discounts, weekly digests, or just system notifications.
What to check in your signup forms right now
— Checkbox behavior: the opt-in checkbox on every form on your site (signup, checkout, contact form) isn't pre-checked. The user checks it deliberately, on their own.
— Clear, informative copy: next to the form, it's clearly stated exactly what someone is subscribing to and how often emails will arrive.
— The DOI flow works: the automatic subscription confirmation email is configured in Letteros and goes out to the user within 5 seconds of submitting the form.
— Unsubscribe accessibility: the unsubscribe link is visible, added to every email's footer, and lets someone unsubscribe in a single click without needing to log in or enter a password.
— List hygiene: automatic segmentation and deactivation are set up for contacts who haven't shown any activity in the last 4–6 months.
Bottom line
Ethical email marketing isn't just about following the rules — it's a direct economic benefit for the business. By building your list responsibly, you're investing in your domain's long-term reputation. Email providers will trust your campaigns, keeping you in the inbox, and engaged subscribers will pay you back with high conversion and steady ROI growth.