# Deliverability

Authentication, sender reputation, and the mailbox-provider rules that decide whether your email reaches the inbox at all. The hard floor every program now has to clear.

Email deliverability coverage: Gmail and Yahoo sender requirements, SPF, DKIM, DMARC, one-click unsubscribe, spam-rate thresholds, and list hygiene.

**Canonical:** https://campaigncompass.co/topics/deliverability