B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Current
20%
20% -- list growth reduction from double optin for Double opt-in email lists (2026)
Implementing double opt-in reduces email list growth by 20% to 30%.
- Reported as a range of 20% to 30%
Attribution:
View source
Lighthouse Research Team
Last verified:
·
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Source verified
Evidence graded
Value
20%
Unit
Percentage
Data Vintage
2026
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
45
Freshness
95
Source
v12.ai
Primary
Tier C
https://v12.ai/email-marketing-best-practices-boost-open-rates-by-50/ ↗
Source Article
Email Marketing Best Practices: Boost Open Rates 50% | V12 Marketing
Why Email Marketing Still Delivers the Highest ROI in 2026
Email marketing continues to reign as the most cost-effective digital marketing channel, delivering an average return of $42 for every $1 spent. Yet many businesses struggle with one critical metric that determines campaign success: open rat…
Original Research
v12.ai
· Original study ↗
Methodology
Range 20%-30%; midpoint extracted
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
Double opt-in email lists: 20% list growth reduction from double optin. Source: v12.ai (2026). Via Lighthouse Intelligence -- https://lighthousedata.io/data/double-optin-list-growth-reduction
HTML Embed
<blockquote cite="https://lighthousedata.io/data/double-optin-list-growth-reduction" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>20%</strong> -- list growth reduction from double optin for Double opt-in email lists<br><small>Source: v12.ai (2026) · <a href="https://lighthousedata.io/data/double-optin-list-growth-reduction" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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