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Card class: Non-Hero • Category: Email Marketing
Spam complaints plotted over time. This is the most reputation-sensitive line you have: the thresholds that mailbox providers enforce are tiny, so even a small upward drift is serious.

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At a glance

The time-series of spam complaints across the selected period, where a complaint is a recipient marking your email as junk. This is the single most reputation-sensitive deliverability signal, because the thresholds mailbox providers enforce are extraordinarily low: major providers such as Gmail and Yahoo expect bulk senders to stay well under a 0.3% complaint rate and to treat 0.1% as the line you should never approach. That low ceiling is why this card uses a trend, not just a rate: a complaint line drifting upward, even by amounts that look trivial, can be the difference between landing in the inbox and landing in spam. A rising trend almost always traces back to consent, relevance, or cadence: people complain when they did not expect the email, do not find it relevant, or are getting too many. Treat any sustained climb here as urgent, well before it shows up as a deliverability drop.
What it countsThe count of spam complaints per period bucket, plotted as a line over the selected window.
API endpoint + statistics fieldPOST /api/campaign-values-reports and POST /api/flow-values-reports, returning the spam_complaints statistic (with spam_complaint_rate available) per bucket.
Email vs SMS aggregationEmail only. SMS complaints and opt-outs are handled through carrier and consent mechanisms, tracked separately under the SMS channel.
MPP impactNone. Apple Mail Privacy Protection inflates opens, not complaints, so this line is unaffected by MPP.
Chart typeLine.
Time window30D vsP
Alert triggerAny sustained upward movement in spam complaints, given how low the provider thresholds are, which signals consent, relevance, or cadence problems and real reputation risk.
Rolesowner, marketing

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Calculation

Calculated automatically from your Klaviyo data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.

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Worked example

An illustrative food brand that raised its send cadence and re-engaged a long-dormant segment in the same fortnight. Reading the dashboard on 14 Apr 26 for the trailing 30 days (14 Mar 26 to 12 Apr 26), the spam-complaint line by week looks like this (illustrative figures):
WeekDeliveredSpam complaintsComplaint rate
14-20 Mar 2690,000180.02%
21-27 Mar 2691,000190.02%
28 Mar-3 Apr 2692,000640.07%
4-12 Apr 2693,000930.10%
Baseline complaints ~18 per week (~0.02%)
Week 4 reaches 93 complaints, a ~0.10% rate
0.10% looks tiny but is exactly the Gmail / Yahoo danger line
Five observations:
  1. The numbers look small but the trend is alarming. Going from 18 to 93 complaints a week is a roughly fivefold rise, and the rate reaching 0.10% touches the threshold mailbox providers treat as a red line. Small absolute numbers, serious signal.
  2. The trend matters more than any single day. A single complaint is noise; a line climbing week after week is a pattern. This card exists precisely to catch that drift while the absolute numbers still look reassuringly low.
  3. The cause is usually consent, relevance, or cadence. The rise here coincides with a higher cadence and a re-engaged dormant segment, which is the textbook recipe: people who had forgotten they subscribed, hit more often, are the most likely to click the spam button.
  4. Complaints are heavier than unsubscribes. An unsubscribe is a clean exit; a spam complaint actively tells the mailbox provider your mail is unwanted, which damages reputation far more. A rising complaint trend can suppress inbox placement for your entire list, not just the complainers.
  5. The fix is to pull back and re-permission. Slow the cadence to the dormant segment, send a sunset or re-permission flow, and remove anyone who does not re-engage. Watch this line alongside Unsubscribe Rate; a healthy correction often shows complaints falling as unsubscribes briefly rise, which is the right trade.

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Sibling cards merchants should reference together

Spam Complaint Trend is the most reputation-sensitive line. Pair it with these:
CardWhy pair it with Spam Complaint Trend
Spam Complaint RateThe proportion behind the line. The trend shows direction; the rate shows where you sit against the 0.1% and 0.3% thresholds.
Sender Reputation RiskThe composite warning. Complaints are one of the heaviest inputs to a reputation-risk flag.
Deliverability DropThe downstream consequence. A rising complaint trend is one of the surest precursors to inbox placement falling.
Unsubscribe RateThe cleaner exit. Encouraging unsubscribes over complaints is the right trade, so watch them together.
Email Health KPIsThe deliverability dashboard. Complaints sit alongside bounces and delivery as a combined health read.
Bounce TrendThe companion hygiene trend. Rising complaints and rising bounces together is a strong combined warning.

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Reconciling against Klaviyo

Where to look in Klaviyo:
  • Klaviyo → Analytics → Performance, then the spam-complaints or complaint-rate metric over time.
  • Klaviyo → Campaigns and Klaviyo → Flows, then a specific send’s analytics, where complaints are broken out per send.
  • Klaviyo → Analytics → Deliverability, for the reputation context and provider-level signals behind a rising line.
Why our number may legitimately differ:
ReasonDirection of divergence
Provider feedback lag. Complaints arrive via mailbox-provider feedback loops, which report on a delay. The most recent bucket can under-count until complaints finish landing.The latest bucket reads low until feedback arrives.
Time zone. Vortex IQ buckets by UTC day; Klaviyo uses your account time zone. A complaint near midnight can fall into a different period.Either direction, usually marginal.
Not all providers report. Only providers with feedback loops report complaints, so true complaints to non-reporting providers are invisible on both sides.Both read low versus reality.
Campaign plus flow scope. This card blends campaigns and flows. A campaign-only view will read lower.Ours reads higher than a campaign-only view.
Page caps. Values reporting pages at 50 records per pull, so very high send volumes can see slight aggregation truncation.Ours can read marginally low for heavy senders.

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Known limitations / merchant FAQs

My complaint numbers are tiny, why is this card flagged as serious? Because the thresholds are tiny too. Mailbox providers such as Gmail and Yahoo expect bulk senders to keep complaints well under 0.3% and treat 0.1% as a line you should not cross. At those levels a handful of extra complaints a week is a meaningful move, which is why even small rises here warrant attention. How is this different from Spam Complaint Rate? This card is the trend, the count plotted over time so you can see direction. Spam Complaint Rate is the proportion against your send volume, which tells you where you sit relative to the provider thresholds. The trend warns you something is moving; the rate tells you how close to the edge you are. Why are complaints worse than unsubscribes? An unsubscribe is a clean exit that signals you to stop. A spam complaint actively tells the mailbox provider your mail is unwanted, which is a direct hit to sender reputation and can lower inbox placement for your whole list. Making unsubscribing easy, so people choose it over the spam button, protects deliverability. What usually causes a rising complaint trend? Consent, relevance, or cadence. People complain when they did not expect the email (weak or stale consent), do not find it relevant (poor targeting), or get too many (over-sending). Re-engaging long-dormant contacts at a high cadence is a common trigger, because they have forgotten they subscribed. The latest week looks low, is the trend over? Maybe not. Complaints arrive through provider feedback loops on a delay, so the most recent bucket often under-counts and fills in over the following days. Give the right edge of the chart time before deciding the trend has reversed. Does this include SMS spam reports? No. This card is email spam complaints only. SMS opt-outs and carrier-level reports are handled through the SMS channel and reported separately.

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Tracked live in Vortex IQ Nerve Centre

Spam Complaint Trend is one of hundreds of KPI pulses Vortex IQ tracks across Klaviyo and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English. Start for free or book a demo to see this metric running on your own data.