1. Standardize Fax Number Formatting
Normalize all fax numbers to a consistent format. For example:
Remove all non-numeric characters: +1 (800) 123-4567 → 18001234567
Use country codes fax lists consistently (especially for international campaigns)
Remove extensions or notes from number fields
Pro tip: Use Excel or Google Sheets with formulas or scripts to clean columns efficiently.
2. Remove Obvious Duplicates
Use built-in spreadsheet or CRM tools:
Excel: Data > Remove Duplicates
Google Sheets: Data Cleanup > Remove duplicates
CRMs and database platforms often offer deduplication tools by phone, fax, email, etc.
3. Detect “Fuzzy” or Near-Duplicates
Duplicates may appear under:
Slightly different business names: “ABC Corp” vs. “A.B.C. Corporation”
Multiple entries with the same fax but different contacts or branches
Use tools like OpenRefine, Data Ladder, or dedupe.io for fuzzy matching.
4. Cross-Check Multiple Fields
Don’t dedupe by fax number alone — validate by:
Business name
Location/address
Contact person
Email/domain name
This helps preserve useful multi-contact records while removing real duplicates.
5. Scrub Against Do-Not-Fax and Opt-Out ListsRemove:
Recipients who have opted out
Numbers listed on internal or external Do-Not-Fax registries
Numbers from previous campaigns that bounced or failed
Keep an "unsubscribe suppression list" and regularly update it.
6. Purge Outdated or Inactive Contacts
Remove entries with invalid or disconnected fax numbers
Use a fax verification tool or test-sending to validate questionable entries
Delete businesses that no longer exist (check via online lookup or business databases)
7. Tag and Segment for Future Use
As you clean, tag contacts by:
Industry
Region
Opt-in status
Engagement level
Segmentation improves targeting and reduces waste.
8. Automate with Scripts or Tools
For large lists, consider:
Python scripts (e.g., using pandas and fuzzywuzzy)
CRM automation
Zapier or Make to connect list sources and deduping logic
Final Checklist Before Sending
All numbers are properly formatted
No exact or fuzzy duplicates
All recipients have valid consent (or EBR if applicable)
Opt-out list has been applied
Clear tags for industry/region/interest
Bottom Line:A clean, deduplicated fax list saves you money, improves ROI, and keeps you compliant with regulations like the TCPA and Junk Fax Prevention Act. Even a quick cleanup pass can significantly boost your campaign performance.
Want a spreadsheet template or deduplication script to get started?