Metrics
What is Unsubscribe Rate?
The percentage of delivered recipients who opt out of future messages via an unsubscribe link or header.
Unsubscribe rate is calculated as unsubscribes divided by delivered (or sometimes sent) emails, expressed as a percentage. It counts both one-click List-Unsubscribe header actions and clicks on in-body unsubscribe links. A healthy rate is typically well under 0.5 percent, and a sudden spike signals a targeting, frequency, or relevance problem before complaints escalate.
Why it matters for cold email
In cold email an unsubscribe is the lighter-touch alternative to a spam complaint, and a rising rate is an early warning that your list or messaging is off before mailbox providers start routing you to spam. Honoring opt-outs immediately is also a legal requirement under CAN-SPAM and GDPR, so unsubscribe handling must be reliable, not just measured.
Related terms
Stop guessing at deliverability.
Scheduler Zero handles authentication, warmup, and sender reputation so your cold email lands in the inbox, not the spam folder.