Email bounce rate is the percentage of emails you sent that were returned as undeliverable instead of reaching an inbox. You calculate it by dividing the number of bounced emails by the number of emails sent, then multiplying by 100.
Hard bounces and soft bounces
Not every bounce means the same thing, and the difference changes what you should do.
- Hard bounce: a permanent failure. The address does not exist, the domain is gone, or the receiving server refuses it outright. Remove these addresses and never send to them again.
- Soft bounce: a temporary failure. The mailbox is full, the server is busy, or the message was too large. These can succeed later, but an address that soft bounces again and again should be treated like a hard bounce.
When people talk about a bounce rate problem in outreach, they usually mean hard bounces, because those come from bad data.
Why it matters when you do outreach
Mailbox providers watch how your sending behaves. Sending to lots of addresses that do not exist looks like what spammers do: they buy or guess lists and blast them. A high bounce rate tells receiving servers that you do not know who you are writing to.
That damages your sender reputation, and reputation follows you. Once it slips, even your emails to real, valid people are more likely to land in spam. So a bad list does not just waste those bounced sends. It drags down the ones that should have worked.
There is a practical cost too. Gmail, Outlook and most SMTP providers can limit or suspend accounts that bounce heavily. If you send from your main business mailbox, that is a real risk to your day-to-day email.
A common rule of thumb in cold email is to keep hard bounces under about 2 percent, and to stop and investigate well before 5 percent. These are working guidelines, not official limits, and every provider sets its own thresholds.
A worked example
Say you run a small web design studio and send a first step to 400 local businesses.
- 400 emails sent
- 22 hard bounces (addresses that do not exist)
- 6 soft bounces (full mailboxes, temporary errors)
Total bounce rate: 28 / 400 = 7 percent. Hard bounce rate: 22 / 400 = 5.5 percent.
That is too high. If you also have follow-up steps queued, such as a drip campaign with three more emails, those steps will try the same bad addresses again unless they are removed. The right move is to pause, remove the 22 hard bounces, check where the list came from, and verify the rest before continuing.
Now imagine the same 400 contacts verified first. Verification flags 30 as invalid and 15 as risky. You drop the invalid ones, hold the risky ones back, and send to 355. If 3 bounce, your rate is under 1 percent, and you protected the account you send from.
Common mistakes that push bounce rate up
Sending to unverified lists. Addresses go stale as people change jobs and businesses close. A list that was fine six months ago may not be today.
Guessing addresses. Writing to firstname@company.com because it seems likely is a quick way to collect hard bounces.
Buying lists. You cannot know how old or how clean they are, and there are often legal questions as well. See GDPR for outreach and check the rules that apply where you and your recipients are.
Sending a big batch from a new account. A fresh mailbox has no track record, so a burst of bounces hits harder. Start small and build up.
Ignoring bounces between steps. If your follow-ups keep firing at addresses that already bounced, you repeat the damage with every step.
Counting catch-all addresses as safe. Some domains accept mail for any address at the server level and bounce it later. Verification tools often mark these as risky. Treat them with care rather than as confirmed.
What to do next
- Verify before every campaign, especially for older lists or imports. It costs far less than a damaged sender reputation.
- Remove hard bounces immediately and keep them off future lists.
- Send risky addresses separately in small batches, or skip them, so they cannot drag down your main send.
- Use fresh data. Pulling leads close to the time you send means fewer stale addresses. Defining tight criteria with firmographics also helps you avoid junk entries.
- Watch the first step closely. Check bounce numbers after the first few dozen sends, not after the whole list is done.
- Spread sending across days with sensible daily limits per mailbox rather than one large blast.
Where GetClient fits
In GetClient you can pull leads from Google Maps, run email verification on the list, and send the campaign from your own connected Gmail or SMTP accounts in the same place, so you are not exporting a CSV between a scraper, a verifier and a sender and losing track of which addresses were checked. Campaign analytics show how each campaign is performing, and send-day limits by weekday help you pace a new account. New accounts start with 100 free credits; see plans and credits for the rest.
Whatever tool you use, the habit is the same: clean list in, bounces checked early, bad addresses removed for good.