Skip to content
← MailMaid Academy
List hygiene

Clean a CSV list without losing your original data

Short answer

A practical import, review and export workflow for real contact lists.

Keep a working copy#

Start with a copy of the original export. Include the stable contact ID, source and consent fields if they are already present. The email column alone is rarely enough to reconnect results to the right record later.

Map before you clean#

Check the header setting and selected email column. Review several rows, especially files with quoted commas or line breaks. MailMaid preserves original columns and adds separate result columns so a correction never silently rewrites source data.

  • Choose the email column.
  • Review exact duplicates and format failures.
  • Export unchecked, risky and invalid segments separately.

Review the writeback#

A cleaned export is not permission to delete every rejected contact. Preserve the source record, suppress where appropriate and record the reason. Reconcile by contact ID before updating a CRM. Keep a dated copy of the decisions for the person responsible for the next send.

Keep reading

List hygiene

A suppression list should survive every cleaning pass

A new verification result must not erase a recipient’s choice.

2 min read
List hygiene

Carry consent and suppression through an ESP migration

A clean list is only one part of a safe migration.

2 min read
List hygiene

Deduplicate carefully: case, dots and plus tags

Convenient normalization rules can merge different recipients.

2 min read