Cleaning a Lusha or Seamless.AI Export Before You Email It

Before emailing a Lusha or Seamless.AI export, choose one work address per contact, remove duplicates across all your exports, verify every address close to the send date, and import only valid addresses into your sequence. Data tools check addresses at some point before export, but people change jobs and mailboxes close in the meantime.

The same steps apply to any contact data tool, including combinations of several.

Why exported contacts still need a check

Issue	Why it happens
Person left the company	Data was correct when collected but is out of date now
Address guessed from a pattern	Some tools infer addresses and label confidence differently
Catch-all domains	Cannot be confirmed by any tool
Personal addresses mixed in	Some exports include personal emails alongside work ones
Same person from several tools	Teams combine sources and duplicate contacts

How fast B2B contact data decays explains the ageing problem.

Step 1: Standardise the export

Different tools name columns differently. Before merging:

1. Rename columns to one standard: email, first name, last name, company, domain, title.
2. If there are several email columns, choose the work address as the send column.
3. Keep any confidence or status column from the data tool for reference; it is useful when comparing with verification results.

The CSV merge tool combines exports with different columns, and extract email and phone from CSV pulls contact fields out of messy files.

Step 2: Separate work and personal addresses

Run the email column through the free vs business email filter. For B2B cold outreach, most teams send only to work addresses. If you plan to use personal addresses, check the rules for the recipients' countries first; see GDPR and B2B cold email.

Step 3: Dedupe across every export

1. Dedupe within the new file with the duplicate email remover.
2. Subtract your master list of already-contacted people with compare two email lists.
3. Subtract your suppression list: unsubscribes, bounces, customers.

Merging lead lists without duplicates covers multi-source lists in more depth.

Step 4: Verify

Upload the cleaned file and sort the results:

Result	Action
Valid	Import into the sequence
Catch-all	Separate low-volume step or skip
Risky	Usually skip for cold outreach
Unknown	Re-check later
Invalid	Suppress; optionally verify an alternative address for that contact

When the data tool's confidence label and the verification result disagree, trust the more recent check, and treat the contact as risky if in doubt.

Step 5: Track results by source

If you use more than one data tool, add a "source" column before verifying. After verification, count invalid and catch-all rates by source. That tells you which tool works best for your market, which is more useful than any vendor's accuracy claim. How to check a lead list's quality shows how to sample before buying more.

Step 6: Import and send carefully

• Import the valid file into your sequencer, mapping personalisation columns.
• Start at normal daily volume and check bounces on the first batch.
• Add catch-all contacts later, in smaller batches.

The guides for Instantly, lemlist and Smartlead cover each tool's import format.

Phone numbers from the same export

Contact data tools also export phone numbers. If you plan to call:

• Format them consistently with the phone number formatter.
• Check validity and line type with the bulk phone number validator.
• Follow calling rules for each country, including Do Not Call lists where they apply.

A validity and line-type check confirms the number is correctly formed and what kind of line it is registered as. It does not confirm the number is in service.

Checklist

• Standard columns, one work email per contact
• Personal addresses separated
• Deduped against master list and suppression list
• Verified; valid imported, catch-all held back
• Results tracked by data source

Keep the data tool's credits working for you

Most contact data tools charge per contact revealed or exported. Deduping against your master list before exporting, where the tool allows it, saves those credits too. Some tools let you exclude contacts already in your CRM; use that setting if it exists. The less overlap you export, the less you pay in both tools.

Verify the export

Upload your cleaned export on the verify page. You get 100 free email checks when you sign in with Google, no card, so you can test a sample from each data source before verifying the whole file.