Your email platform flagged your account for bounces. Here's what to do.

You sent a campaign, and now there's a warning in your dashboard. Your bounce rate is too high, your sending's been paused, or your account is "under review". Maybe your bounce rate came in at 6% and you don't know if that's bad. (It is.)

It's fixable. Here's what to do, in order.

1. Don't send anything else yet

The worst move is to send again to the same list and hope. Every extra bounce makes the next review harder, and it tells inbox providers like Gmail that you don't know who's on your list.

If your platform has paused you, read the message carefully. Most will tell you what they want before you can send again, usually a cleaned list and an explanation of where the addresses came from.

2. Find out what kind of bounces they were

Open the bounce report for the campaign. You're looking for two things.

Hard bounces are permanent. The mailbox doesn't exist or the domain can't receive email. These are the ones that got you flagged.

Soft bounces are temporary. A full inbox, a busy server, a message that was too big. A few of these are normal.

If most of your bounces are hard, the problem is the list. If most are soft and they're all at one company or one provider, the problem might be on their side, and it's worth waiting a day before you change anything.

3. Work out where the bad addresses came from

This matters because your platform may ask, and because it tells you what to fix so it doesn't happen again. The usual suspects:

• An old list you hadn't emailed in a year or more
• A sign-up form with no confirmation step, so typos and fake addresses went straight in
• A contest or discount pop-up that attracted throwaway addresses
• Contacts imported from somewhere else, like a spreadsheet, an event or a CRM
• A bought or rented list. If this is it, stop using it. Most platforms ban them outright, and no amount of cleaning makes it safe.

Look at the addresses that bounced. If they're mostly typos like gmial.com or hotmal.com, it's your form. If they're old company addresses, it's age.

4. Clean the whole list, not just the bounces

Your platform has already removed the addresses that bounced. The problem is the ones you haven't sent to yet. If 6% of one segment bounced, the segments you didn't email this time probably have the same rot in them.

Export everything and run it through a verifier before you send again. A verifier checks each address against its mail server and tells you which ones will bounce, without sending anything.

With ListBouncer you upload the CSV and get every address back in one of five groups, with the reason for each:

• Safe: confirmed by the mail server. This is your clean list, and it's what your first send back should go to.
• Major provider (Yahoo, Outlook, Hotmail and AOL): these providers don't let anyone confirm a mailbox. They get their own download. Mail to them usually delivers, but send to them as a separate segment once your first send looks healthy, so you can see exactly where any bounces come from.
• Will bounce: remove these from your email tool.
• Risky and Unknown: leave these out of your first send back. You can add them back later once your account's in good standing.

New accounts get 100 free credits, so you can see what's in a list before you pay for anything. If you just want to check a few addresses, the free email checker does 10 a day without an account.

5. Remove the bad addresses in your email tool

Don't just import the clean list on top of the old one. The bad addresses are still in there and they'll get emailed next time.

Instead, take the Will bounce file and unsubscribe, archive or suppress those addresses in your email tool. How you do that depends on the platform. We've written up the steps for MailPoet, Mailchimp, Klaviyo and others in Removing bad addresses from your email tool.

6. Reply to the review (if there is one)

If your account is under review, keep your reply short and specific. Something like:

The bounces came from an older segment we hadn't emailed since last year. We've verified the full list, removed every address that would bounce, and we're only sending to confirmed addresses from now on. We've also added a confirmation step to our sign-up form.

Platforms want to see that you understand what happened and that you've changed something. They don't want a long apology.

7. Come back slowly

When you're cleared, don't blast the whole list on day one.

• Send to your most engaged subscribers first: people who opened or clicked in the last 90 days.
• Watch the bounce rate on that send. With a clean list it should be well under 2%.
• Widen the audience over the next few sends.

8. Stop it happening again

• Add a confirmation step to your sign-up forms. A fake address can't confirm, so it never gets on your list.
• Clean before any send to an old segment. Six months without a send is a good trigger.
• Clean every few months if you collect a lot of sign-ups. Lists decay even when every address started out real.

Can a verifier be trusted?

Fair question. We tested ListBouncer on a list where we knew the right answer for every address, including fake and dead addresses we sent real mail to so we could see them bounce. Every checkable address came back right, and none of the bad ones were marked Safe. The full results are on our accuracy page.