The Cost of a Dirty List
Every email sent to an invalid address costs you (or your ESP) compute resources. Every bounced email hurts your sender reputation. Every duplicate send annoys a customer who's already on your list. Every "Hi [FIRST_NAME]" sent to a record where first name is blank is embarrassing.
Cleaning your customer database before a campaign isn't just best practice — it's the difference between a campaign that performs and one that wastes budget.
The Four-Part Pre-Campaign Cleanup
Part 1: Deduplication
Sohovi automatically finds every duplicate in your dataset — including near-matches — and shows you exactly which rows are affected.
Export your customer list to CSV. Check for duplicate email addresses. A customer who appears three times will receive your email three times, increasing unsubscribes and spam reports.
Sort by email address. Consecutive duplicates are immediately visible. Keep the most recently updated record, delete the rest.
Also check for duplicates by phone number for SMS campaigns.
Part 2: Invalid and Undeliverable Emails
Remove or flag:
- Addresses without an @ symbol
- Addresses with obvious typos in the domain (gmial.com, yhaoo.com)
- Role accounts (info@, admin@, noreply@) — these rarely engage with marketing
- Any address previously hard bounced (your ESP should track these)
For a list you haven't emailed in 6+ months, run it through an email verification service before sending.
Part 3: Incomplete Required Fields
For personalization to work, you need the fields you plan to use. If your campaign says "Hi " and 20% of records have no first name, you'll send "Hi ," to those contacts.
Audit required fields: first name, last name, email (obviously), and any segmentation field you plan to use. Decide how to handle blanks: use a fallback ("Hi there,"), fill in from another source, or exclude those records from the send.
Part 4: Suppress the Right People
Before any send:
- Remove all unsubscribes
- Remove all previously hard-bounced emails
- Remove anyone flagged as a competitor, press, or internal team member (if your list has them)
- Remove anyone on a legal hold or with a complaint on file
Most ESPs handle unsubscribes automatically. But manual suppression lists — competitors, employees, certain domains — need to be applied manually.
The Post-Campaign Cleanup
After every campaign, update your database:
- Mark new hard bounces as invalid
- Mark new unsubscribes
- Update engagement scores (opens, clicks)
A database that gets cleaned before and after every campaign stays clean over time.
