How to lower bounce rate

You got Sustained permanent bounce rate is above 2% or above 5%. Permanent bounces stayed at that share of sent mail across consecutive windows with enough volume. Low-volume days stay neutral and do not create this alert.

5% is an error. 2% is a warning. Both mean the list has addresses that do not exist (or reject the mailbox).

This is not inbox placement. It is hard failures after send.

What to change

1. Open Settings → Deliverability and confirm the bounce windows.
2. Stop the next campaign/workflow send to the same dirty list.
3. Remove or suppress permanent-bounce addresses. Lumail already suppresses them after a permanent bounce — do not re-import them.
4. For the next send, exclude:
   • role accounts you never confirmed (info@, admin@) if they bounce
   • old exported lists
   • purchased or scraped addresses
5. Prefer confirmed opt-in for new subscribers.

If you imported a CSV, run a small verified segment first. Do not “clean” by blasting the whole file.

What does not fix it

• Changing DKIM/DMARC. Auth issues are separate alerts.
• Sending more mail to dilute the rate. That makes enforcement worse.

After it recovers

The alert resolves only after consecutive adequate windows stay below 2%. One good day is not enough.

Related

• How to lower complaint rate
• Sender Health
• Account Verification