1. Executive Summary
Purpose. Determine whether domain reputation and consistency outweigh message content in driving inbox placement, bounce rate, and spam likelihood.
“Deliverability climbs with reputation and rhythm — not with message flair.”
2. Hypothesis & Theoretical Framework
Hypothesis. Inbox placement correlates more with domain reputation and consistency than with message content.
Theory Link. Providers’ ML classifiers reward consistent sender patterns and established domain signatures; volatility is treated as suspicious.
Predicted Outcome. Aged, consistent domains yield 20–30% higher inbox placement and 40% lower bounce/spam ratio vs. new domains, regardless of identical content.
Potential Impact. Improves Apex Engine’s send-time reputation module and provides priors for domain warm-up pacing.
Domains: new vs aged · Message: constant (plain) · Scheduler: scheduler.emails for cross-domain parity · Reward: inbox rate → bandit_feedback.reward
3. Data & Metrics
- Inbox Placement (%): Delivered to inbox vs. spam.
- Bounce Rate (%): Failed deliveries (hard + soft).
- Spam Rate (%): Filtered into spam folders.
- Open Rate (%): Human engagement proxy.
4. Experiment Execution Plan
- Define Variants: Domains — new (age < 14d) vs aged (>90d).
- Sample Size: 4,000 emails per domain type.
- Duration: 10 days continuous.
- Measurement: Logged via send_events → inbox, spam, bounce, open.
- Analysis: Compute inbox rate correlations vs domain consistency & reputation weight.
5. Results (Aggregate)
| Domain Type | Inbox % | Spam % | Bounce % | Open % |
|---|---|---|---|---|
| New | 63.4 | 28.6 | 8.0 | 18.5 |
| Aged | 89.2 | 8.4 | 2.4 | 31.8 |
6. Data Analysis & Interpretation Framework
- Raw Analysis: Aggregated per domain group.
- Model Feedback Loop: Retrain send-time and reputation weights using domain consistency as a feature.
- Synapse Peer Review: Flag for inclusion in “Deliverability Maturity Matrix”.
- System Learning Integration: Update scheduler bias toward stable send volume.
7. Insights & Discussion
- High-volume, stable aged domains outperform any content tweaks on new domains.
- Bounces and spam correlation: R² = 0.74, supporting consistency → trust linkage.
- Open rates mirror inbox lift, proving accessibility, not creativity, drives engagement.
8. Ethical Considerations
- Focus on sender system behavior.
- Transparency in how reputation affects deliverability.
9. Contribution to the Synapse Ecosystem
- Data Improvement: Strengthens domain reputation priors in the Apex engine.
- Educational Value: Provides “Warm-up Blueprint” guidance for members.
- Innovation Signal: Next: adaptive warm-up pacing via reinforcement learning.