Email deliverability
Deliverability fixes for Omnisend and Klaviyo senders: domain authentication, list clean-up, a controlled warm-up and new sending habits, so your flows and campaigns reach people who actually want them.
The short answer
If campaign open rates sit below 15–20%, drop suddenly without a change in content, or flows that used to earn go quiet, inbox placement is the first thing to check. Most problems come from sender reputation and sending behaviour rather than a broken setting, which is why fixing them takes a plan, not a single toggle.
Opens drop across campaigns and flows at the same time, especially at Gmail, Outlook or iCloud addresses.
Hard bounces, deferrals or mass rejections from one mailbox provider point to a reputation or list-quality problem.
Welcome and cart flows open at a fraction of normal rates. The same flows at healthy open rates can often double their revenue with no new traffic.
What causes it
In most audits, every technical check passes and the problem is still there. That's because mailbox providers judge how you send and how people react, not just how your domain is set up.
Every send to people who haven't opened or clicked in months tells Gmail and Outlook your mail isn't wanted.
Jumping from your usual volume to the whole list for Black Friday or a launch looks like spam behaviour, even to a clean list.
Contacts from old platforms, giveaways or events carry invalid addresses and spam traps that damage reputation fast.
Missing or misaligned SPF, DKIM and DMARC records now lead to filtering or outright rejection at Gmail and Yahoo.
Daily sends to everyone raise unsubscribes and spam complaints. Frequency should follow engagement, not the promo calendar.
Flows and campaigns that are nothing but a code and a button get less engagement, and less engagement means lower placement.
How recovery works
Cleaning a list before authentication is fixed, or ramping volume before the list is clean, wastes weeks. The order matters.
01
Diagnose
SPF, DKIM and DMARC checked, blocklists and Google Postmaster Tools reviewed, and bounce and engagement data read per mailbox provider.
02
Clean
Invalid addresses, likely spam traps and long-term unengaged contacts removed or moved into a separate win-back track.
03
Warm up
Sending rebuilt from the most engaged contacts outward, in steps sized to what mailbox providers will trust.
04
Monitor
Engagement-based segments and sending rules put in place so the problem doesn't come back.
Sender requirements
Since 2024, Gmail and Yahoo enforce rules for anyone sending in bulk to their users. Most e-commerce brands on Omnisend or Klaviyo fall into this group.
Requirement
What it means
What we check
SPF and DKIM
Your domain proves the email really comes from you.
Both records set up for your sending platform and passing.
DMARC
A published policy telling providers how to treat mail that fails authentication.
Record in place, aligned with your From domain, with reports reviewed.
One-click unsubscribe
Subscribers can opt out in one click, and requests are honoured within two days.
List-Unsubscribe headers present on campaigns and flows.
Spam complaint rate
Kept below 0.3%, with Google recommending under 0.1%.
Complaint trends in Google Postmaster Tools and your platform's reports.
Valid DNS
Sending domains and IPs resolve correctly.
Checked alongside your platform's sending infrastructure.
Benchmarks
Rough ranges we use in audits for e-commerce senders. Read them together: one number on its own rarely tells the whole story.
Metric
Healthy
Investigate
Campaign open rate
25% and up
Below 15–20%
Welcome and cart flow open rate
40–60%
Below 25%
Spam complaint rate
Under 0.1%
Above 0.3%
Hard bounce rate
Under 1%
Above 2%
Apple Mail Privacy Protection inflates open rates, so opens are always read alongside clicks, revenue and results per mailbox provider.
Free deliverability audit
You get a written summary of what's healthy, what's hurting inbox placement and the order to fix it in. If you want to fix it yourself, you can.
Request the free auditFAQ
Why are my Omnisend emails going to spam?
Usually because of sender reputation: sending to contacts who haven't engaged in months, ramping volume too fast, or weak authentication. Content can play a part, but it's rarely the main cause when every technical check passes.
How long does it take to fix deliverability?
Authentication fixes take effect in days. Rebuilding reputation usually takes several weeks of disciplined sending, depending on how damaged it is and how large the list is.
Should I clean my email list?
Yes, if you have a lot of old or unengaged contacts. A verification pass removes invalid addresses and likely spam traps, and unengaged contacts get a short win-back before being suppressed. A smaller, engaged list almost always earns more.
Is a DMARC policy required?
Gmail and Yahoo require bulk senders to publish a DMARC record along with SPF and DKIM. Without it, more of your email gets filtered or rejected.
Can you fix deliverability without changing platforms?
Yes. Deliverability recovery works the same in Omnisend and Klaviyo. Switching platforms doesn't fix a reputation problem on its own, because the reputation is tied to your domain.
Free audit
Share your store and platform. You'll get a clear read on inbox placement and the first three fixes to make.
