A message delivered to Inbox at 09:03 can be moved to Spam at 09:45. Providers run second-pass classifiers minutes to hours after delivery — engagement-based reclassification, complaint-driven reclassification, content-based sweeps. Most placement tools take one snapshot at delivery and call it done.
What post-send tracking does
- Re-checks folder placement at +15 min, +1h, +4h, +24h, +72h.
- Per-seed, per-provider history.
- Alerts on folder transition (Inbox → Spam, Primary → Promotions).
- Aggregate session report: “of 80 seeds that delivered to Inbox, 6 got reclassified to Spam within 24h.”
Why reclassification happens
- Complaint-driven: a user clicks Report Spam. Gmail can apply that signal to similar in-flight mail for up to 24h.
- Engagement-based: Gmail's post-delivery model reads how the user interacts with mail and reclassifies similar past mail accordingly.
- Content sweeps: if a second-pass filter identifies a pattern in fresh spam, it applies to recent history.
- Blocklist propagation: a domain added to a filter's blocklist after your send causes reclassification of your mail in-flight.
What to do when a reclassification alert fires
- Pause the active sequence. Don't pile on to a degrading send.
- Check complaint rate in your ESP and Postmaster (it probably spiked).
- Review the template for the trigger that emerged.
- Wait 24–48h for signal to normalise before resuming; rewrite content if the alert persists across retests.
Turn on post-send tracking
Run a test and enable post-send tracking for that session. Free, per-seed detail, webhook alerts available.
FAQ
How long is tracking active?
72 hours by default. Extended windows available for monitoring specific campaigns.
Does this work for real outbound or only test messages?
For test messages through our seed network. For real outbound, use a combination of placement tests and Postmaster filtered-rate monitoring — we tie both together in the dashboard.
Do I get webhooks?
Yes — on the free tier for email alerts, paid for high-frequency webhook delivery to your systems.
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