Delivery rate only tells you the receiving server accepted the message. Where it went next, inbox, a tab or spam, is placement. A campaign can show 99% delivered while half of it sits in spam at one provider, which looks like a bad reply rate when it is really a deliverability problem.
How placement is measured
- Seed tests: send to a set of test mailboxes at each provider and see where the message lands. Quick, but seeds do not behave like real recipients.
- Engagement by provider: compare how many real recipients at Google, Microsoft, Yahoo and others still open and reply against each provider's normal level. Slower, but it reflects your real audience.
- Provider tools: Google Postmaster Tools shows domain reputation and spam rate for senders with enough Gmail volume.
Replies at Google recipients hold steady at the usual level. At Microsoft recipients, engagement falls to a third of its baseline in a week. Placement has dropped at Microsoft, not everywhere.
How to fix a drop
Slow down at the provider that dropped, check SPF, DKIM and DMARC, remove links and images from the copy, check it for spam words, and keep email warmup running. Routing rules can keep mail to that provider on your healthiest mailboxes while it recovers.
In ZicReach, inbox placement is read from engagement by mailbox provider, with no seed lists to maintain; changes inside normal noise are marked as such, and a provider well under its baseline gets a plain next step. See it on the warmup and deliverability page, and use the spam word checker on the copy.