Bounce rate is the share of sent emails that couldn’t be delivered and came back with an error. It is usually calculated as bounced emails divided by emails sent. Some reports combine hard and soft bounces in one number; others show them separately. Separate figures are more useful because the two kinds mean very different things.
Hard bounces are permanent failures, such as an address that doesn’t exist. Soft bounces are temporary, such as a full mailbox or a server that is briefly unavailable. A rising hard-bounce rate almost always points to list quality: old addresses, typing mistakes at sign-up, or contacts imported from a source that never collected real consent. A spike in soft bounces at one provider can instead signal throttling or a reputation problem with that provider.
Mailbox providers watch bounces closely because spammers send to lists full of dead addresses. A hard-bounce rate that stays above about 2% is a warning sign, and much higher figures can lead providers, and responsible email platforms, to slow or pause your sending. Well-kept lists that collect addresses through confirmed opt-in often see hard-bounce rates well under 1%.
Bringing the rate down is mostly about prevention. Suppress hard bounces immediately so you never mail them again, stop soft-bouncing addresses after repeated failures, verify old or imported lists before sending, and use double opt-in or a real-time check on sign-up forms to catch mistyped addresses like “gmial.com”.
A furniture store in Hyderabad sends to 8,000 contacts and gets 240 hard bounces, a 3% hard-bounce rate. Most come from a 2019 trade-fair list. The store suppresses those addresses, verifies the rest of that segment before the next send, and the following campaign’s hard-bounce rate falls to 0.4%.
MailNesto shows hard and soft bounce rates separately for the last 30 days, suppresses hard-bounced addresses, and treats an address as bounced after three soft bounces within 30 days.