Require an import dossier

Before accepting a file, ask for the business owner, data source, collection dates, brands/purposes disclosed, exact signup language and notice version, confirmation method, jurisdictions, last send, prior provider, complaint/bounce history, unsubscribe process, and contractual transfer rights. “Customers” or “verified leads” is not sufficient provenance.

Reject purchased, scraped, appended, or partner data that lacks clear recipient permission for this sender and purpose. A vendor asserting that addresses are deliverable does not supply consent.

Secure and profile the file

Upload through an authenticated, size-bounded, malware/formula-safe workflow. Parse in staging, never directly into a live campaign. Count malformed addresses, domains, duplicates, internationalized forms, age buckets, missing consent fields, and unexpected columns. Restrict access and set deletion for the source file.

Do not send SMTP probes or confirmation mail merely because rows exist. Network verification requires its own authorization and still cannot prove permission.

Reconcile non-send decisions

Match the import against central and provider suppressions, complaints, permanent failures, account deletion, and brand/list opt-outs. Suppression wins over an older imported active flag. Preserve source IDs and times so decisions can be traced; do not erase duplicates until histories are merged.

Quarantine rows with missing or conflicting provenance. Give an accountable reviewer a summary, not a button that defaults uncertainty to approved.

Stage a controlled test

If the import is approved, choose a small cohort with the clearest recent permission. Use stable authenticated infrastructure and a message that reminds recipients of the expected relationship without inventing it. Verify unsubscribe before sending. Define complaint, bounce, and support stop conditions.

Monitor by source segment. A high permanent-failure or complaint rate is evidence to pause the import, not a reason to keep sending until the file is “cleaned.”

Preserve the decision

Store importer, approver, provenance, counts accepted/quarantined/rejected, suppression reconciliation, test result, and final scope. Delete rejected/source files on schedule. The import is safe only when every active row has explainable permission and every applicable non-send decision survived. Deliverability tools cannot convert an unauthorized list into an authorized one.