Omnisend is one of the most popular email marketing platforms for e-commerce brands. Its automation workflows, segmentation tools, and SMS capabilities make it a favourite for Shopify and WooCommerce stores. But none of that power matters if your list is dirty.
A bounce rate above 2% signals to inbox providers like Gmail and Yahoo that something is wrong with your sending practices. Hit 5% and you risk account suspension inside Omnisend itself. The culprit is almost always the same: unvalidated contacts that were collected through signup forms, imported CSV files, or third-party integrations without any real-time verification at the point of entry.
This guide walks through exactly how to clean your Omnisend list and keep your bounce rate under control.
Why Bounce Rate Matters in Omnisend
Every email that bounces is a small signal to inbox providers that your list hygiene is poor. Accumulate enough of those signals and your domain reputation suffers. When domain reputation drops, even your good contacts stop seeing your emails in the primary inbox. They go to promotions, or worse, spam.
Omnisend enforces a hard bounce threshold. Accounts that exceed it get flagged and may be paused while support reviews your sending practices. Recovering from that takes time and often requires you to prove the list has been cleaned before sending resumes.
Soft bounces (temporary failures like a full mailbox) are less dangerous but still worth tracking. A contact that soft-bounces repeatedly is likely a dead address and should be treated like a hard bounce.
The Two Types of Problematic Contacts on Your Omnisend List
Before cleaning, it helps to understand what you are actually removing.
Hard bounces are permanent delivery failures. The address does not exist, the domain has expired, or the mailbox has been closed. These contacts should never be emailed again.
Risky or catch-all addresses are the trickier category. These are addresses where delivery cannot be confirmed in advance because the receiving server accepts all email regardless of whether the mailbox is real. They might deliver, or they might bounce silently. E-commerce lists tend to accumulate a lot of these from checkout flows and lead magnets.
Tools like standard email verifiers will mark these as “unknown” or “accept-all” and leave the decision to you. That is not good enough for a high-volume Omnisend sender. You need a tool that can actually verify whether catch-all addresses are live.
Step 1: Export Your Omnisend List
Log in to Omnisend and navigate to Audience in the left sidebar. Select All Contacts and use the filter to segment by subscription status. You generally want to export contacts with the status “Subscribed” since those are the ones you will be mailing.
Click Export and download the CSV. Omnisend exports will include the email address, subscription status, signup source, and any custom properties you have added.
Step 2: Validate the List with Scrubby
Once you have your CSV, upload it to Scrubby. Scrubby specialises in verifying catch-all and risky email addresses, the category that standard validators leave as unknowns. By actually testing deliverability at the mailbox level, Scrubby classifies each address as deliverable, undeliverable, or risky with a confidence score.
The output gives you three actionable buckets:
- Safe to send: confirmed deliverable addresses you can mail with confidence
- Do not send: hard bounces, invalid addresses, and known spam traps
- Risky: catch-all addresses that Scrubby could not confirm. You can choose to suppress these or run a re-engagement sequence before emailing them
A typical e-commerce list that has not been cleaned in 12 months will have between 15% and 30% of contacts in the risky or invalid category. Removing or suppressing these before your next campaign can drop your bounce rate dramatically in a single send.
Step 3: Build a Clean Suppression List
After validation, export the “do not send” addresses from Scrubby as a separate CSV. In Omnisend, navigate to Audience and use the Import Contacts function to upload these addresses with the status set to Unsubscribed.
This is important: do not delete these contacts outright. Setting them to unsubscribed keeps them in your Omnisend contact history so that if the same address ever re-enters your list through a new signup, Omnisend will recognise that it was previously suppressed.
For the risky bucket, consider a different approach. Create a separate segment in Omnisend for these contacts and send a re-confirmation email before your next main campaign. Anyone who clicks or replies gets moved to your active list. Everyone else stays suppressed.
Step 4: Add Real-Time Validation to Your Signup Forms
Cleaning an existing list is a one-time fix. The more durable solution is preventing bad addresses from entering your list in the first place.
Omnisend has a native signup form builder but does not offer real-time email validation at the form level by default. You can connect Scrubby’s API to your forms to validate each address the moment a visitor types it in. The API returns a verdict in under a second, allowing you to block invalid addresses and prompt the visitor to correct a typo before they submit.
For Shopify stores in particular, this is a high-value integration. Checkout flows and abandoned cart capture forms are the most common sources of bad email data on e-commerce lists.
Step 5: Set a Cleaning Cadence
Even a healthy list decays over time. Industry data suggests that between 20% and 25% of email addresses become invalid within a year. People change jobs, abandon free email accounts, or simply stop using an address they signed up with.
A quarterly cleaning cadence works well for most Omnisend senders. High-volume stores with large acquisition budgets may want to validate monthly, especially if they run paid social campaigns that feed large numbers of new contacts into Omnisend every week.
A good signal to trigger an unscheduled clean: any campaign where your bounce rate climbs above 1.5% for the first time. That is early enough to fix the problem before Omnisend flags the account.
Combining Omnisend Segmentation with Validation
One underused tactic is combining Omnisend’s built-in engagement segmentation with external validation. Omnisend lets you segment by opens, clicks, and last purchase date. If you filter for contacts who have not opened an email in 180 days and have never purchased, that cohort is your highest-risk segment for stale or invalid addresses.
Run just that segment through Scrubby before a major campaign like a Black Friday send. You will validate a fraction of the list (the most likely problem contacts) rather than re-validating your entire database, which keeps costs down while still protecting your sender reputation.
What a Clean Omnisend List Actually Looks Like
After cleaning, you should see:
- Bounce rate below 1% on most campaigns
- Open rates rising, because a smaller, more engaged list increases the percentage of people who actually open
- Lower spam complaint rates, because fewer contacts who never intended to sign up are receiving your email
- Consistent inbox placement, since Gmail and Yahoo reward senders whose lists show good engagement signals
The relationship between list quality and deliverability is direct. Every invalid address you remove is a small improvement to your sender score. Over time, these improvements compound.
A Note on Risky Emails in E-commerce
E-commerce stores tend to have a higher proportion of catch-all addresses than B2B senders. This happens because many small businesses use Google Workspace or Microsoft 365 with catch-all routing enabled, so anyone at the company can receive email at any address on the domain.
Standard verifiers classify these as unknowns and recommend you skip them. That advice is conservative but costly because it means leaving a significant portion of your real, engaged customers out of your campaigns. Scrubby’s catch-all verification actually probes these addresses to determine whether they are live, so you can mail the ones that are real while suppressing the ones that are not. It is one of the most practical ways to recover leads that other tools throw away.
If you are running Omnisend for an e-commerce brand and have never validated your catch-all contacts, that is likely the single highest-ROI action you can take on your email program today.
Summary
Cleaning your Omnisend list is not a complex process, but it does require the right tool for the job. Standard validators leave too much on the table by marking catch-all addresses as unknowns. A specialist like Scrubby resolves that ambiguity, giving you a cleaner, more actionable list.
The process: export from Omnisend, validate with Scrubby, import suppressions back, add real-time validation to your forms, and set a quarterly cleaning cadence. Done consistently, this keeps your bounce rate low, your sender reputation healthy, and your campaigns landing where they should.
Kristel K.
Content Strategist