B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Recent
0.1%
0.1% -- recommended max spam complaint rate for Email senders (expert-recommended target) (2025)
Most experts agree email senders should strive for a spam complaint rate of 0.1% or lower.
Attribution:
View source
Lighthouse Research Team
Last verified:
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Source verified
Evidence graded
Value
0.1%
Unit
Percentage
Data Vintage
2025
Entity
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
50
Source Trust
60
Citation Chain
20
Independence
30
Methodology
35
Freshness
95
Source
WP Mail SMTP
Primary
Tier C
https://www.tryletterhead.com/blog/the-hidden-fix-for-falling-newsletter-engagement-email-deliverabi… ↗
Source Article
The Hidden Fix for Falling Newsletter Engagement: Email Deliverability
The Hidden Fix for Falling Newsletter Engagement: Email Deliverability
When newsletter operators notice a drop in engagement, most jump to one conclusion: poor content.
But, what if the real problem is that your finely-crafted emails aren’t actually reaching your audience? Email Tool Tester’s study …
Original Research
WP Mail SMTP
· Original study ↗
Methodology
Best-practice target attributed to 'most experts' and cited via WP Mail SMTP guide; article undated, vintage approximated to collection year.
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
Email senders (expert-recommended target): 0.1% recommended max spam complaint rate. Source: WP Mail SMTP (2025). Via Lighthouse Intelligence -- https://lighthousedata.io/data/recommended-max-spam-complaint-rate
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<blockquote cite="https://lighthousedata.io/data/recommended-max-spam-complaint-rate" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>0.1%</strong> -- recommended max spam complaint rate for Email senders (expert-recommended target)<br><small>Source: WP Mail SMTP (2025) · <a href="https://lighthousedata.io/data/recommended-max-spam-complaint-rate" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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