Deliverability
Since the Google and Yahoo bulk-sender rules of February 2024, inbox placement is a hard technical gate, not a soft best practice.
4 metrics
- Domain health
- Configuration and reputation state of sending domains and mailboxes.
- Benchmark 2–3 mailboxes/domain; 10–20 cold emails/mailbox/day
- Infrastructure design lets you scale volume without concentrating reputation risk.
- Spam rate (Postmaster)
- Spam complaint rate as reported by Google Postmaster Tools.
- Benchmark Below 0.30% hard line; target <0.10%
- The metric mailbox providers actually enforce against you.
- Warmup ramp
- The 2–4 week schedule bringing a new mailbox up to sending volume.
- Benchmark 2–4 weeks, then ongoing 20–30 warmup emails/day
- Skipping warmup gets a new domain flagged immediately.
- Bounce rate
- Share of sends rejected (see Outbound systems).
- Benchmark Under 2%
- The fastest way to wreck a domain; gate every send on list hygiene.
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