The share of recipients who opt out of a campaign - the honest verdict on whether your cadence and content are earning their place in the inbox. The benchmark that matters is not sends per week, it is unsubscribes per send: your audience will tell you when you are over-mailing them, one opt-out at a time. The mistake is blasting the list daily with discount codes to hit a send cadence, which trains customers to ignore you or only buy on discount. Restraint is a strategy - fewer, better sends keep open rates high, unsubscribes low and revenue per send strong.
Benchmark. Ecommerce campaigns average roughly 0.2-0.4%, and most guidance treats a rate that stays above about 0.5% as a warning. Quad Lock was comfortable under about 1% because it sent rarely and every email had a reason. Watch the trend: unsubscribes that climb as you add sends mean you are sending too often or the content is not earning the open. An unsubscribe beats a spam complaint, so make leaving easy - and err on restraint, because every email should have a reason to exist.