The percentage of recipients who opt out of receiving further emails after a given send, calculated as unsubscribes divided by emails delivered.
Why it matters
A rising unsubscribe rate is an early warning sign of content fatigue, irrelevant targeting, or sending frequency that's higher than an audience wants — and ignoring it can gradually erode a list's overall size and quality.
In a sentence
"Unsubscribe rate spiked after we increased send frequency to three times a week, so we scaled it back."
Related terms
- Antonyms: Subscribe rate, opt-in rate (people choosing to join a list, the inverse action).
- Often confused with: Spam complaint rate (unsubscribing is a controlled, intended opt-out action; a spam complaint is a recipient actively flagging an email as unwanted, which carries more serious deliverability consequences).
- Synonyms: Opt-out rate.