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Card class: Hero • Category: Email Marketing
abuse_reports / emails_sent. Above 0.1% Gmail / Yahoo de-prioritise the sender domain. MC-DEL-002 fires.

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At a glance

The percentage of recipients who marked an email as spam, aggregated across every campaign and Customer Journey email in the period. Computed as SUM(abuse_reports) ÷ SUM(emails_sent) × 100. Above 0.1% Gmail and Yahoo de-prioritise your sender domain immediately, and Mailchimp’s own Compliance team flags accounts at sustained 0.05%+ for review. Audit MC-DEL-002 fires here. Spam-complaint rate is the strictest deliverability number you have, an order of magnitude tighter than bounce rate.
What it countsSUM(reports.abuse_reports) ÷ SUM(reports.emails_sent) × 100 across every campaign + Customer Journey email in the period.
API endpointMarketing API v3, GET /3.0/reports/{campaign_id} returns abuse_reports (integer count). Customer Journey emails use GET /3.0/automations/{workflow_id}/emails/{email_id}/reports.
What “abuse” meansRecipient clicked “Mark as spam” / “Report spam” in their email client, AND their ISP forwarded the complaint via Feedback Loop (FBL) to Mailchimp. Gmail, Yahoo, AOL, Outlook all participate in FBL; some smaller ISPs don’t, so the figure is a lower bound.
Audience-based scopeAggregates across every audience. Per-audience complaint rate (in Audiences Overview) often shows new-imported audiences dramatically higher, those subscribers don’t recognise the sender.
Channel scopeEmail only. SMS doesn’t have an equivalent.
Hard threshold significanceGmail’s published threshold is 0.1% (1 complaint per 1,000 sends). Yahoo’s is 0.3%. Mailchimp Compliance reviews at 0.05% sustained. A single bad campaign can push you over for the day even if 30D average is healthy, watch the per-campaign view, not just the aggregate.
MPP impactNone. MPP affects opens, not clicks-on-spam-button.
Bounce handlingBounces don’t count as complaints. The denominator (emails_sent) excludes bounces; the numerator (abuse_reports) only includes deliberate spam-flag actions.
Attribution modelNot applicable.
CurrencyNot applicable.
Time window30D vsP (default 30D vs the prior 30D)
Alert trigger>0.1% (drives sentiment_key: spam_rate). MC-DEL-002 fires here. The 0.1% threshold is the lower of “Mailchimp Compliance flag” and “Gmail throttle”; treat it as red-line.
Rolesowner, marketing, engineering

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Calculation

Calculated automatically from your Mailchimp 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

A small DTC home-fragrance brand running on Shopify with Mailchimp Standard, single consumer audience of 28,000. Window 03 Apr 26 to 02 May 26.
CampaignSentSpam complaintsComplaint %
Spring scents launch27,20080.029%
Mother’s Day promo27,400140.051%
Re-engagement series email 16,400320.500%
Welcome (Customer Journey)1,18010.085%
Account total62,180550.088%
Five observations:
  1. The headline 0.088% is just under the 0.1% red-line, with no safety margin. One single complaint-heavy send tips the account over. The re-engagement campaign at 0.5% is doing all the damage; without it, the rest of the account would be at a healthy 0.04%.
  2. Re-engagement campaigns ALWAYS spike complaint rate. Recipients who haven’t engaged in months don’t recognise the sender, and “Mark as spam” is a faster path to silence than finding the unsubscribe link. Re-engagement is a calculated trade, you accept a complaint-rate spike in exchange for a cleaner go-forward list. The mistake is sending re-engagement at full audience volume; small batches (<2,000 at a time) keep the complaint count below FBL-trigger thresholds.
  3. One Mother’s Day complaint moved the rate by 0.004 pp. That sounds tiny but accumulated across the period it’s the difference between safe and flagged. Spam complaint rate is brutally sensitive at small numbers. A 28,000-subscriber list only needs 28 total complaints in a 30D window to breach 0.1%.
  4. The Welcome Customer Journey at 0.085% is unusual. Welcome emails should complain at 0.01-0.03% because recipients just opted in and remember signing up. 0.085% on a Welcome suggests either (a) the signup form lacks a clear “you’ll receive marketing emails” notice, or (b) the from-name doesn’t match the brand name on the website (e.g. signed up at “Brand X” but the email comes from “Marketing Team @ ParentCo”).
  5. Gmail’s threshold is 0.1% but Mailchimp Compliance reviews at 0.05% sustained. Even with the headline at 0.088%, this account is in Mailchimp’s risk zone. Compliance may issue a list-cleanse notice that requires action within 7 days. The fix here is stop the re-engagement campaign and split it into smaller weekly batches.

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Sibling cards merchants should reference together

Spam rate is the strictest deliverability number; pair these:
CardWhy pair it with Spam Complaint Rate
Mailchimp Bounce RateThe other half of the deliverability pair. ISPs throttle on EITHER bounce >5% OR spam >0.1%. Both must stay green.
Mailchimp Unsubscribe RateTrades against complaints, recipients who unsub don’t complain. A clear unsubscribe link in every email pulls complaint rate down.
Mailchimp Suppressed MembersSpam-complainers are auto-suppressed by Mailchimp. Watch for sudden suppression spikes after a complaint-heavy send.
Mailchimp Email-Attributed RevenueRevenue follows deliverability with a 2-3 week lag. Spam breaches today predict revenue dips later.
Mailchimp Open RateIf opens fall and complaints rise together, the audience genuinely doesn’t want the content. Both signal “stop sending until cleansed”.
Mailchimp Audience Growth RateFast list growth from low-quality sources (paid leads, list rentals) drives complaints. Watch growth and complaint rate together.
Mailchimp Sender Reputation AlertComposite alert (bounce >5% OR spam >0.1%). Treat as one early-warning signal.
Mailchimp Spam Spike AlertThe 24-hour anomaly detector. Catches a single bad campaign before the 30D rate notices.

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Reconciling against the vendor’s own dashboard

Where to look in Mailchimp’s own dashboard: Mailchimp → Campaigns → Reports → individual campaign → Performance tab for per-campaign abuse complaints, with a complaint count and rate. Mailchimp → Audience → Audience Health shows audience-level complaint trends. Other Mailchimp views that look like the same number but aren’t:
  • Account → Sender Reputation: blended reputation score, includes complaints + bounces + engagement. Not the same as complaint rate alone.
  • Campaigns → individual report → “Subscribers who clicked Mark as Spam”: a list of complainers, useful for investigation but not the rate.
Why our number may legitimately differ from Mailchimp’s dashboard:
ReasonDirection of divergence
Time-zone. Mailchimp uses account timezone; Vortex IQ uses UTC.±0.005 pp at the boundary
FBL latency. Some ISPs (notably Microsoft) batch Feedback Loop reports. A complaint clicked yesterday may not appear in Mailchimp’s data for 2-12 hours.None on a 30D total; up to ±0.01 pp on the 7D view
Page caps. Engine pages campaigns 10 per call up to 5 pages. >50 distinct sends per 30D shows truncation.Vortex IQ slightly off for high-cadence senders
Customer Journey aggregation. Per-journey rollup in Mailchimp UI sometimes averages complaint rate across email steps; Vortex IQ pulls per-step counts and sums.None on the headline
Anonymous complainers. Some ISPs strip the recipient address from FBL reports for privacy; Mailchimp counts the report but can’t suppress the address. The complaint rate is correct but the suppression list grows slower than expected.None on this rate; affects suppression count
Cross-connector reconciliation: Spam complaint rate is a Mailchimp-internal deliverability metric. Closest cross-references:
CardExpected relationshipWhat causes legitimate divergence
Gmail Postmaster Tools (no connector)Gmail’s “User-reported spam rate” should track within ±0.05 pp of this card’s Gmail-only slice.Postmaster reports per-domain; Mailchimp aggregates across all ISPs.
klaviyo.klv_spam_rateWhen both ESPs run on the same store, rates should track within ±0.03 pp.Different segmentation strategies expose different parts of the audience.

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Known limitations / merchant FAQs

Why is my complaint rate so much stricter than my bounce rate threshold? Bounces are SMTP-layer (delivery failures, often technical). Spam complaints are recipient-action (intentional “this is unwanted”). ISPs treat complaints as a much stronger negative signal because they carry direct user intent. Gmail’s threshold is 0.1% (1 complaint per 1,000 sends). Bouncing 1 in 1,000 is fine; 1 spam complaint per 1,000 means 1 person consciously rejected your email, which is enough for Gmail to start inboxing your future sends to spam. What’s a healthy steady-state complaint rate? For consumer DTC, 0.01-0.04% is healthy. For B2B, 0.005-0.02% (lower because corporate users complain less, they delete or filter). Charity / non-profit lists run lower again, around 0.005%. The 0.1% alert threshold is the upper limit before Gmail throttles, not a target. If you’re consistently in the 0.05-0.08% band, you have a list-quality problem that hasn’t bitten yet. My complaint rate spiked after a re-engagement campaign, is that normal? Yes, expected. Re-engagement campaigns pull dormant subscribers back into the inbox; many of those subscribers have forgotten signing up and “Mark as spam” is faster than “Unsubscribe”. The strategic answer: split re-engagement into batches of <2,000 over a 4-6 week window, monitoring complaint rate after each batch. The tactical answer: include “We noticed you haven’t engaged in a while” copy in the email and put the unsubscribe link in the FIRST paragraph, not the footer. Why don’t I see all my complaints in Mailchimp? Some smaller ISPs (Apple, smaller corporate domains) don’t participate in Feedback Loop, so complaints from those recipients aren’t reported. Mailchimp’s count is a lower bound of total complaints. The figure is still useful as a relative metric over time even if absolute count is incomplete. Will Mailchimp suspend my account if I cross 0.1%? Not immediately at 0.1%, but Mailchimp Compliance reviews accounts at sustained 0.05%+. Crossing 0.1% on a single campaign typically triggers an automated email asking for action; sustained 0.1% over 30 days can lead to send-pause. Mailchimp’s TOS requires accounts to stay under 0.5% complaint rate as a hard ceiling. A subscriber complained but said they didn’t, how is that possible? Three causes: (a) shared mailbox where someone else clicked spam; (b) mobile mail apps where “Archive” and “Spam” buttons are visually adjacent and easily confused; (c) Gmail’s “Move to spam” suggestion for low-engagement senders, some users follow the prompt without thinking. None of these are reversible at the FBL layer; the report stands regardless of intent. Does this card include Customer Journey complaints? Yes. Both regular campaigns and Customer Journey email-step complaints sum into this rate. Welcome emails should complain at <0.03%; abandoned-cart emails at 0.05-0.10% (slightly higher because abandoners often weren’t sure they wanted marketing in the first place). Should I worry about a single complaint on a 200-recipient send? Mathematically yes, that’s 0.5% on the campaign. Practically, Mailchimp’s API rounds rates per-campaign, and small-list complaint rates are noisy. Look at the 30D blended rate, not single-campaign figures, for trend-tracking. But for compliance and Compliance review, even small-list breaches can trip flags. My account uses a custom domain via Mailchimp Authentication, does that affect complaints? The complaint rate is the same but the impact is contained. With a custom authenticated subdomain, complaints harm that subdomain’s reputation only and don’t bleed into your primary store domain. This is essential for any merchant sending >100k/month, set up authentication before complaint rate becomes a problem, not after.

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Tracked live in Vortex IQ Nerve Centre

Spam Complaint Rate is one of hundreds of KPI pulses Vortex IQ tracks across Mailchimp 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.