As the founder of a SaaS language learning platform, I rely on Lemon Squeezy to manage user subscriptions. Currently, I use checkout[email] to prefill the email field during checkout. This improves the user experience — but since users can still modify the email before completing payment, it introduces serious consistency issues.
Why this matters:
A user can pay with a different email than their app account, breaking the link between app data and payment.
One user might create multiple accounts in my app and use the same email to pay for all of them.
If one of these subscriptions is later canceled, and I reconcile via the API/webhooks using customer_id or email, all related accounts may be incorrectly marked as unpaid.
This has already created edge-case issues in production. For SaaS apps with automated reconciliation, it’s critical to enforce a one-account → one-email → one-payment structure.
Suggested feature:
Add a parameter like checkout[disable_email_editing]=true to lock the email field in the checkout form, ensuring it cannot be modified by the user.
This would help:
✅ Maintain data integrity
✅ Prevent accidental or intentional misuse
✅ Reduce support overhead
✅ Improve integration reliability for SaaS apps
Thanks for considering! Lemon Squeezy has been a great platform to work with — this feature would make it even stronger for developers managing user-linked subscriptions.