FAQ
Common questions about measuring email transit performance across providers.
What does “email transit time” mean?
Transit time is the elapsed time between defined checkpoints in the email journey. We typically report end-to-end transit from message generation to inbox placement, plus sub-stage timings for diagnostic clarity.
What is “generation to acceptance” time?
Generation to acceptance measures how long it takes from when a probe creates/submits a message until the receiving SMTP infrastructure accepts it for delivery. This helps identify sending-side queueing or SMTP handshake delays.
What is “acceptance to inbox” time?
Acceptance to inbox measures post-acceptance processing time, including filtering, routing, and mailbox placement. This phase often varies by provider policy, reputation signals, and traffic conditions.
Why split timing into stages instead of only one total number?
Stage-level timing isolates where latency is introduced. If total transit worsens, stage breakdown quickly shows whether the bottleneck is at sender submission, recipient acceptance, or mailbox placement.
How is delivery success rate calculated?
Delivery success rate is the percentage of probe attempts that reach successful provider acceptance and expected mailbox placement within defined observation windows. We track temporary and permanent failures separately.
Can a message be accepted but still delayed or filtered?
Yes. SMTP acceptance does not guarantee immediate inbox placement. A message may still be deferred, quarantined, throttled, or routed to spam based on downstream checks and provider-specific filtering logic.
Do results differ by provider and region?
Yes. Transit behavior can differ substantially by provider network, geography, traffic profile, and policy settings. Comparing providers using identical probe methodology helps identify meaningful performance differences.
Are these measurements real-time guarantees?
No. Measurements are observational indicators. They show recent performance and trends but do not constitute a guarantee of future latency or placement outcomes in all scenarios.
What does “public-interest” mean in this project?
Public-interest means the project is designed to provide neutral, useful infrastructure visibility for operators, researchers, and the wider community rather than to promote one vendor or platform.
How does being nonprofit affect the work?
As a nonprofit initiative, the focus is on methodological consistency and broad access to findings. Priority is placed on measurement quality and long-term public benefit.
Do you sell or rank providers for commercial gain?
No. The goal is independent benchmarking and reporting. Results are intended to inform operational decisions and research, not paid placement or promotional rankings.