How to clean an email list before a campaign

Why you should clean your list before every campaign

Even lists from 6 months ago can have 5–10% invalid or risky addresses. People change jobs, companies shut down, and domains expire constantly. Sending to a stale list without cleaning it first risks:

• Hard bounces that damage your sender reputation
• Spam complaints from old or incorrect addresses
• Wasted budget sending to addresses no one reads

Step 1: Upload your list

Export your contact list as a CSV from your CRM or ESP. BounceProtect accepts any CSV with an email column — it auto-detects the column name.

Step 2: Review the results

After validation, your emails are grouped into four categories:

Valid — Safe to send. The email has valid syntax, active MX records, and passed all checks.

Invalid — Do not send. The email will hard bounce. Common reasons: no domain records, invalid syntax, mailbox rejected by SMTP.

Risky — Use judgment. The email is technically deliverable but has signals that put your sender reputation at risk. Review the specific reason — a catch-all domain at a verified business is different from a disposable provider.

Unknown — Could not verify. Usually a DNS timeout. Safe to include but monitor bounce rates.

Step 3: Export clean segments

Use the Export button to download only Valid emails, or download all emails with their validation status appended as columns.

Step 4: Suppress invalid and high-risk addresses

Upload your suppression list to your ESP before sending. Most ESPs (Mailchimp, HubSpot, Klaviyo, Instantly) support suppression list imports.

Step 5: Set up ongoing validation

Validate new contacts at the point of capture using the BounceProtect API. This prevents invalid addresses from ever entering your list.