How to Integrate Essential Preorder & Back in Stock with Omnisend
Integrating Essential Preorder & Back in Stock with Omnisend automatically syncs back-in-stock waitlist signups into Omnisend as contacts, so you can trigger nurture flows and restock alerts without any manual export or delay.
Before You Begin
Plan requirement: Connecting your Omnisend account in Settings → Integrations works on every plan, including Free. Choosing Omnisend under Send emails through on a Back in Stock campaign needs the Lite plan or higher. Shopify Flow is a third option there (Beta, Lite or higher), see Shopify Flow triggers and actions.
Omnisend account: You need an active Omnisend account to generate an API key.
Setup
Step 1. In Omnisend, go to Store Settings → API Keys → Create API key. Name it (e.g. "Essential Preorder"), select Contacts and Events permissions, then click Create API key → Copy API key. (Need help? See Generate an API Key in Omnisend)
Step 2. In your Shopify admin, go to Essential Preorder → Back in Stock → General Settings → Integrations.
Step 3. Paste your copied API key into the Omnisend field and click Save.
That is it. The integration is now active.
💡 The Tag field on the Integrations page (default: essential-preorder-back-in-stock) is applied to all enabled marketing integrations. It helps you identify Essential Preorder contacts in Omnisend.
What Data Is Passed
When a customer submits the "Notify Me" form on an out-of-stock product, a contact is created in Omnisend and a custom event fires in real time.
Supported Events
| Custom Event Name | When It Fires |
| essent_back_in_stock_waitlist_joined | Customer submits the "Notify Me" form on an out-of-stock product |
| essent_back_in_stock_waitlist_confirmed | Customer confirms their signup via a GDPR double opt-in email |
Event Properties
Each event includes the following properties:
| Property | Description |
| product_id | The product the customer is waiting for |
| variant_id | The specific variant they signed up for |
| essent_campaign_id | Unique ID of the Back in Stock campaign |
| essent_notification_id | Unique ID of the individual signup |
Building Automation Workflows
Use these events as triggers in Omnisend Automation Workflows:
Nurture flow: Trigger from essent_back_in_stock_waitlist_joined to keep customers engaged while they wait for stock to return.
GDPR-confirmed flow: Trigger from essent_back_in_stock_waitlist_confirmed to reach only customers who have explicitly opted in.
💡 Essential Preorder does not send an event when stock is restored. Back-in-stock notifications are sent from within the Preorder app itself. The Omnisend integration captures waitlist contacts and supports pre-restock nurture sequences.
Frequently Asked Questions
Which Essential Preorder plan do I need?
Any plan. Connecting Omnisend is available on the Free plan. Choosing Omnisend as the sender on a campaign needs Lite or higher.
Does the integration sync historical waitlist subscribers?
No. Only new signups from the moment the integration is activated are synced to Omnisend.
Is the sync real-time?
Yes. A contact and event are created in Omnisend the instant someone submits the "Notify Me" form.
Is there a manual sync option?
No.
The rest of the Integrations page
- Tag: a tag added to every contact the app creates in a connected marketing tool. One tag for all integrations.
- Klaviyo, Mailchimp, Postscript: listed with an API Key field but marked Coming soon. Click Notify me and we email you when one goes live. Until then, use Shopify Flow to pass signups to these tools.
- Request integration: opens a chat with support to ask for a tool that is not listed.