ETechFlow Back-in-Stock Notification

Customers subscribe to out-of-stock products. When stock returns, they get an email.

Standalone-first — works on any Magento 2.4.4+ install without other ETechFlow modules. Integrates richer when paired with NDE / BED / ISP.

Install

composer require etechflow/module-back-in-stock-notification:^1.0
bin/magento module:enable ETechFlow_BackInStockNotification
bin/magento setup:upgrade
bin/magento setup:di:compile
bin/magento cache:flush
# Restart php-fpm to clear OPcache (mandatory on prod with opcache.validate_timestamps=0)

Activate the licence

php tools/generate-license.php --module=back-in-stock-notification --host=<your-domain>

Paste the key into Stores → Configuration → eTechFlow → Back-in-Stock Notification → License Key.

For multi-module customers, paste the bundle key into the Bundle License Key field instead. One key activates every ETechFlow module installed on the host.

Verify

bin/magento etechflow:bisn:verify

Twelve PASS lines means you're good to go.

How it works

1. Customer hits an out-of-stock PDP → a "Notify me when back in stock" form replaces the disabled Add-to-Cart button.
2. Form submit → etechflow_bisn_subscription row created. Anonymous (email only) or customer-linked.
3. Merchant saves stock with qty > 0 → StockSaveObserver enqueues a notification for every subscription matching that product + store.
4. Cron runs every 5 min → QueueConsumer sends batched, rate-limited emails. Default 60 emails/minute.
5. Customer clicks the email → one-click unsubscribe (RFC 8058 compliant) OR goes to the PDP to purchase.

Configuration

Stores → Configuration → eTechFlow → Back-in-Stock Notification:

• License Key — per-module key (or use Bundle License Key for the suite)
• Module Enabled — toggle the whole feature
• Email Rate Limit — emails/minute (default 60). Adjust to your SMTP capacity.
• Subscription Lifetime — auto-expire unredeemed subscriptions after N days (default 180, 0 = never)
• eTechFlow Suite Integrations — NDE / BED / ISP opt-in toggles (hidden if the sibling module isn't installed)
• Notifications — sender email, sender name, email subject template

Compatibility

• Magento Open Source 2.4.4 – 2.4.8
• Adobe Commerce 2.4.4 – 2.4.8
• PHP 8.1 / 8.2 / 8.3 / 8.4
• Hyvä Theme + Hyvä Checkout (PDP form renders via Hyvä-safe block)

Support

[email protected] — please include your license key + Magento version when reporting issues.

Changelog — ETechFlow Back-in-Stock Notification

All notable changes to this module. Adheres to Semantic Versioning.

[1.0.0] — 2026-05-20 — Customer subscribes, gets emailed when stock returns

First commercial release. Solves the universal "customer wanted the product, you were OOS, you lost the sale" problem.

The differentiator vs every existing M2 back-in-stock module

Every existing module on the marketplace shares one or more of these footguns:

1. No queue / no rate limit — popular SKU restocks, module synchronously sends 5,000 emails inside one stock-save observer, breaks the stock-import job. Ours queues and rate-limits.
2. Per-website only, not per-store — multi-store stores send notifications across all stores indiscriminately. Ours is store-scoped.
3. No anonymous subscriptions OR no logged-in linking — either guests can't subscribe (limits lead capture) or logged-in customer subs aren't linked to their account (UX regression). Ours does both, with auto-linking on customer creation.
4. No one-click unsubscribe — required by CAN-SPAM / RFC 8058. Many modules ship without it. Ours has signed-token one-click unsubscribe.
5. No suite integration — pure standalone, so a customer whose drop-ship rules (NDE) say "not eligible" still gets a "back in stock!" email. Ours respects NDE eligibility when installed.

Added

Foundation

• registration.php, composer.json (proprietary licence, soft-deps on NDE / BED / ISP)
• etc/module.xml setup_version 1.0.0
• DB schema: 2 tables.
  • etechflow_bisn_subscription — customer_id (nullable), email, product_id, store_id, subscribed_at, notified_at, unsubscribe_token, status.
  • etechflow_bisn_notification_queue — subscription_id, scheduled_at, attempts, status. Decouples "stock came back" from "email was sent".
• Admin config (etc/adminhtml/system.xml) — License section + General Settings + eTechFlow Suite Integrations + Notifications. Standard 4-section layout.

Licensing + Infrastructure

• Model/LicenseValidator — per-domain HMAC + bundle key. MODULE_ID = back-in-stock-notification. Shares BUNDLE_SECRET_FRAGMENTS with every eTechFlow module.
• Model/Config — license-aware isEnabled(). Soft-detection of optional integrations (NDE, BED, ISP) via class_exists.
• Model/Performance/Profiler — Tideways span helper, tags ETechFlow_BISN_*.

Entities + Service Contracts

• Full Api/Data + Api/Repository contracts for the Subscription entity.
• Model + ResourceModel + Collection + Repository implementations.

Frontend

• Block/Product/NotifyMeForm + template — renders on PDP when product is out of stock. Replaces the disabled Add-to-Cart with a "Notify me when back in stock" form (email + optional first-name).
• Block/Customer/SubscriptionList + template — customer account "My Subscriptions" page. Lists active subscriptions with unsubscribe-from-here button.
• One-click unsubscribe controller — etechflow_bisn/subscription/unsubscribe?token=<signed> validates the signed token, removes the subscription, shows a confirmation page.

Detection + Notification

• Observer/StockSaveObserver — fires on cataloginventory_stock_item_save_after. Cheap: bails immediately if no subscriptions exist for the product. When qty goes from 0 → positive, enqueues notifications.
• Cron/QueueConsumer — runs every 5 min via cron. Pulls due notifications from queue, rate-limited (default 60/min), sends transactional email per subscription, marks as sent. Retries on transient failure up to 3 attempts.
• Model/Notification/BackInStockSender — composes + sends the email. Customisable template via Magento's standard email-template system.
• etc/email_templates.xml — registers etechflow_bisn_back_in_stock template. Default template at view/frontend/email/back_in_stock.html.

Admin

• Magento UI Component listing grid at Sales → Operations → Back-in-Stock Subscriptions: ID, Email, First Name, Product ID, Customer ID, Store View, Status (filterable), Subscribed At, Notified At, per-row Actions (Delete / Cancel).
• Mass actions: Delete (removes audit row), Cancel (keeps audit row, blocks future notifications), Notify Now (force-queues notification — bypasses the qty 0→positive trigger).
• Two ACL resources: subscriptions_delete (Delete + Cancel) and subscriptions_notify_now (force-queue) so you can grant view-only access to most admin roles.
• Source model for the Status column dropdown.

Auto-Link Anonymous Subscriptions

• Plugin/Customer/AutoLinkSubscriptionsPlugin — after-plugin on Magento\Customer\Api\AccountManagementInterface::createAccount. When a guest who previously subscribed by email later registers with the same email, their pending subscriptions auto-link to the new customer (so they appear in My Account → Subscriptions immediately).
• Defensive: never blocks customer creation. Logs failures and continues.

Lifetime Expiry

• Cron/LifetimeExpiryCron — runs daily at 03:00. Updates status from pending|confirmed → expired for rows older than the admin-configurable lifetime (default 180 days, 0 = never expire). Single UPDATE query — index-only on (status, subscribed_at). Logs the affected row count when nonzero.

Double Opt-In Confirmation Email

• Model/Notification/ConfirmSender — sends the confirmation email when the admin "Require Double Opt-In" toggle is on. Best-effort — if SMTP fails, the pending subscription stays in DB so the customer can re-trigger from the PDP form.
• Default template at view/frontend/email/confirm.html (configurable via Marketing → Email Templates).

Optional eTechFlow Suite Adapters

• Model/Adapter/NdeEligibilityAdapter — when NDE is installed + admin opted in, "in stock" is determined by NDE's IneligibilityChecker::isEligible() instead of raw qty > 0. Falls back to direct stock check when NDE isn't present.
• Model/Adapter/BedEtaAdapter — when BED is installed, restock notifications include BED's per-product ETA in the email if the restock is itself a future backorder.
• Model/Adapter/IspStoreAdapter — when ISP is installed, customers can opt to subscribe to a specific pickup-store's stock (not just the global stock).

Verify CLI

• bin/magento etechflow:bisn:verify — 12 checks covering license, config, all 2 DB tables, repository via DI, observer registration, cron registration, email-template registration. Exit 0 on full pass, 1 on any failure.

Standalone-first architecture

Same pattern as ISP. This module works fully standalone — no other ETechFlow module required. The integrations with NDE / BED / ISP are opt-in enhancements soft-detected via class_exists. If the sibling module isn't installed, BISN falls back to its own self-contained logic.

Compatibility

• Magento Open Source 2.4.4 – 2.4.8
• Adobe Commerce 2.4.4 – 2.4.8
• PHP 8.1 / 8.2 / 8.3 / 8.4
• Hyvä Theme + Hyvä Checkout (PDP form renders via Hyvä-safe block)