There’s a familiar pattern in both the Shopify and Klaviyo community forums: a merchant posts, often with some urgency, that their emails were landing fine for months and then suddenly started going to spam, usually right after a big list import, a new app install, or a spike in sending volume around a sale. The frustrating part is that nothing looks obviously broken. The flow is still active, the campaign still sends, Klaviyo shows it as delivered, but customers report never seeing it, or finding it buried in Gmail’s spam or promotions tabs weeks later.
Deliverability problems are rarely caused by one dramatic mistake. They’re almost always the accumulation of several smaller issues that individually seem minor, a missing authentication record, an aging list nobody’s cleaned, subject lines that trip spam filters, that together push your sending reputation below the threshold mailbox providers use to decide inbox versus spam. This post is a structured way to work through that diagnosis rather than guessing.
Start With Authentication: SPF, DKIM and DMARC
This is the most common root cause behind a sudden drop, and it’s worth ruling out first because it’s checkable in minutes.
What to check in your domain’s DNS records:
- SPF (Sender Policy Framework), confirms Klaviyo is authorised to send on behalf of your domain. Klaviyo provides the exact record to add during account setup; if it was set up correctly at first but a domain/DNS provider change happened since (a common trigger when merchants switch domain registrars or add a new app that also modifies DNS), it can silently break.
- DKIM (DomainKeys Identified Mail), a cryptographic signature confirming the email wasn’t altered in transit. Klaviyo generates DKIM keys per sending domain; check under Settings > Domains in Klaviyo that your domain shows as fully verified, not partially configured.
- DMARC (Domain-based Message Authentication), tells receiving mail servers what to do if SPF or DKIM checks fail. A missing or misconfigured DMARC record is increasingly relevant since Google and Yahoo’s 2024 bulk sender requirements made DMARC effectively mandatory for anyone sending meaningful volume to Gmail and Yahoo addresses.
If any of these three show as unverified or missing in Klaviyo’s domain settings, that alone can explain a sharp, sudden deliverability drop, and it’s the first thing to check before looking at content or list health.
Check What Changed Around the Timing of the Drop
Deliverability rarely degrades for no reason. Work backward from when the problem started:
- Did you recently do a large list import or migration? Importing thousands of old, unengaged contacts and emailing them immediately is one of the most common triggers merchants report, mailbox providers see a sudden spike of sends to addresses that don’t open or click, and treat it as a spam signal.
- Did you install or remove an app that touches email, like a review request app, a loyalty programme, or a marketing automation tool that might also be sending from your domain?
- Did your sending volume spike sharply, for example, ramping up campaign frequency heavily around a sale, without a gradual warm-up?
- Did you change your “From” name, sending domain, or Klaviyo account setup recently?
Audit Your List Health
A large but disengaged list is one of the most common underlying causes behind deliverability problems that surface as “suddenly going to spam,” because mailbox providers weight recent engagement heavily when deciding where to route your next send.
Checklist:
- [ ] Segment out contacts who haven’t opened or clicked in 90-180 days and stop sending your regular campaigns to them without a specific re-engagement approach
- [ ] Check your list growth source, did you buy, rent, or scrape a list at any point? (If so, remove it entirely, purchased lists are one of the fastest ways to damage sender reputation)
- [ ] Review your Klaviyo suppression list and confirm hard bounces and previous spam complaints are actually being suppressed, not re-added through imports
- [ ] Set up (or review) a sunset/win-back flow specifically for inactive subscribers rather than treating your whole list as one engagement pool
Review Content Patterns That Trip Spam Filters
Content is a smaller factor than authentication and list health, but it compounds the problem when the other two are already borderline:
- Excessive use of promotional language and symbols (multiple exclamation marks, “FREE,” “$$$,” ALL CAPS subject lines)
- A poor text-to-image ratio, an email that’s a single large image with almost no real text reads as more spam-like to filters than a balanced mix
- Broken or shortened/masked links, especially through third-party link shorteners
- Missing a genuine physical address and clear unsubscribe link (a legal requirement under Australia’s Spam Act 2003 as well as a deliverability signal)
Check Your Sending Reputation Directly
Beyond Klaviyo’s own reporting, use independent tools to see how mailbox providers actually see you:
- Google Postmaster Tools (free, and essential if a meaningful share of your list is on Gmail) shows domain reputation, spam rate and authentication status directly from Google’s perspective
- Klaviyo’s own deliverability monitoring under account health flags obvious issues, but it won’t show you Gmail-specific reputation the way Postmaster Tools does
- A seed list test (sending a test campaign to a spread of Gmail, Outlook, Yahoo test addresses you control) shows you directly where an email lands, rather than relying on inference
The Audit Sequence, Start to Finish
- Verify SPF, DKIM and DMARC are all fully configured and passing in Klaviyo’s domain settings
- Set up or check Google Postmaster Tools for domain reputation and spam rate trends
- Identify what changed in the days/weeks before the drop (import, volume spike, app change)
- Segment and pause sending to unengaged contacts (90+ days no engagement) while you stabilise
- Audit recent campaign content for spam-trigger patterns
- Run a seed list test to confirm actual inbox placement across major providers
- Gradually rebuild sending volume and frequency rather than resuming full volume immediately
When This Points to a Bigger Structural Problem
Sometimes the audit above turns up more than a quick fix, a domain with genuinely damaged reputation, a list that’s been mismanaged for a long time, or Klaviyo flows and campaigns overlapping in ways that are effectively spamming your own customers without anyone noticing. If the diagnosis is more involved than a DNS record fix, that’s a sign it’s worth a proper technical review rather than trial and error, a Shopify audit covers exactly this kind of cross-system diagnosis, looking at your store, apps and marketing stack together rather than each piece in isolation.
FAQ
Why did my Klaviyo emails suddenly start going to spam after months of working fine?
The most common causes are a broken or newly-required authentication record (SPF, DKIM or DMARC), a large list import sent to without proper segmentation, or a sharp increase in sending volume without gradual warm-up. Work through authentication first since it’s quick to verify.
Does DMARC actually matter for a Shopify store’s marketing emails?
Yes, increasingly so. Since Google and Yahoo’s 2024 bulk sender requirements, a missing DMARC record is a common cause of inbox placement problems specifically for high-volume senders, most active ecommerce stores now fall into that category.
Will removing inactive subscribers hurt my email revenue?
Usually not meaningfully, because subscribers who haven’t engaged in 90+ days are rarely converting from campaigns anyway, and keeping them on your active send list actively damages the deliverability of the emails going to your genuinely engaged subscribers.
How long does it take to recover sender reputation after a deliverability drop?
There’s no fixed timeframe, it depends on the severity of the issue and how quickly the underlying cause is fixed, but expect gradual rather than overnight recovery, typically over several weeks of clean sending patterns and reduced volume to unengaged contacts.
Can a Shopify app cause my emails to go to spam?
Indirectly, yes. Apps that also send email from your domain (review requests, loyalty notifications, some subscription apps) can affect your domain’s overall sending reputation, even if Klaviyo itself is configured correctly. Check what else is sending mail on your domain when diagnosing a sudden drop.
Get a Proper Diagnosis, Not a Guess
Deliverability problems compound quickly the longer they go unaddressed, and DIY fixes based on generic advice often miss the actual root cause. If your Klaviyo emails are landing in spam and you want a structured technical diagnosis across your Shopify store, domain and marketing stack, book a Shopify audit and we’ll find the real cause.
