How Mailcheck Helped 553 Businesses Boost Deliverability with Smarter Email Validation

4 min read

Email marketing still works in 2025, but only if your emails actually land in inboxes. Bad data is the silent killer of ROI: fake signups, disposable accounts, and role-based emails drag down your sender reputation, increase bounce rates, and burn through your marketing budget. That’s exactly why 553 businesses trusted Mailcheck through our AppSumo campaign. With over 553 lifetime deals sold, Mailcheck proved it’s not just another validator, it’s a smarter, API-first way to keep your list clean for good. In this post, we’ll break down why validation matters, what makes Mailcheck different, and how our unique pricing model helped hundreds of companies secure millions of lifetime email checks.

🚀 Why Email Validation Is Essential.

Even the best-crafted campaign fails if your list is filled with junk. Here’s why validation is no longer optional:

Protect deliverability: ISPs downgrade your reputation if too many emails bounce.
Save money: Stop paying to send to invalid addresses.
Filter at the source: Prevent fake users and bots from ever entering your CRM.
Increase conversions: Focus on real people who actually engage with your brand.

🛠 What Mailcheck Does Differently

Unlike legacy validation tools that rely only on SMTP pings (and often return false results), Mailcheck combines advanced algorithms with real-time detection.

Here’s how it works:

Bulk validation: Upload a CSV and get instant results with a Trust Rate Score per email.
Real-time API integration: Add our API to your signup forms to validate every new email before it hits your database. API docs
More accurate results: Less than 3% error margin compared to 20–30% with many competitors.
Privacy-first: Hosted on Google Cloud with GDPR compliance, your data is never shared. Mailcheck doesn’t just say “valid/invalid”. It flags disposables, risky domains, and role-based accounts like admin@ or support@. That’s the detail email marketers need to protect their lists.

📊 AppSumo Campaign Results: 553 Codes Sold.

Our AppSumo launch proved that marketers are hungry for smarter validation:

553 lifetime codes sold
Lifetime access to limited amount of checks
Future updates included Marketers didn’t just buy a tool, they bought peace of mind.

💰 Pricing: Flexible Lifetime Model.

During the AppSumo campaign, we introduced a pricing structure that made sense for everyone, from solopreneurs to enterprise teams:

$59 for 1 lifetime code → 2,000,000 checks
Stack up to 5 codes → 10,000,000 checks
Lifetime access (no recurring fees) This flexibility meant small teams could start lean, while larger senders stacked codes to scale validation across millions of addresses.

🔌 How to Integrate Mailcheck

Integration is simple:

Bulk Upload: Drop your CSV or TSV file into the dashboard, and download a cleaned version with scores.
API Validation: Use our REST API at signup or checkout to filter out invalid signups instantly. Full API reference
- Example: Validate emails in real time and block disposable or risky ones.
Ongoing Monitoring: Revalidate older lists periodically to prevent list decay.

This dual approach (bulk + API) ensures you’re covered both for legacy data and new signups.
🎯 What Early Adopters Saw.

One standout client (KingBillyCasino.com) shared their results:

Before Mailcheck, conversion from registration to deposit was just 1%.
After integrating Mailcheck and additional fraud filters, that number jumped to 4–5%. That’s the difference between sending campaigns into the void and reaching real, engaged players.

📈 Final Thoughts

Email validation is no longer a “nice to have”. It’s a core part of modern marketing infrastructure. With Mailcheck, you get:

Cleaner lists → better deliverability
Real-time protection against bad signups
A lifetime pricing model that scales with you
Developer-friendly API and documentation 553 companies have already joined us through AppSumo. Now it’s your turn to make every email count. 👉 Start cleaning your list today at Mailcheck.co.