How to find missing emails in a contact list (and clean the rest before you send)

Every sales and marketing team has one: the spreadsheet exported from an old CRM, a trade show, a webinar and three people's LinkedIn notes. Some rows have an email. Some have a name and a company and nothing else. Some are people who left two years ago.

Before you send anything to it, here's how to fix it.

Step 1: Dedupe first

Sort by email, then by first name, last name and company together. Merge duplicates, keeping the most recent job title. There's no point enriching the same person twice.

Step 2: Standardise the columns

You need, at minimum: first name, last name, company, company website (the domain), job title, email, country. Split "Full name" into first and last. Put the domain in its own column: it's how every enrichment tool matches a company.

Step 3: Verify the emails you already have

Run them through an email checker. You'll get back roughly four groups:

Result	What to do
Valid	Keep
Invalid	Remove, then try to find a new address for that person
Catch-all or unknown	Send in small batches, watch bounces
Role address (info@, sales@)	Keep only if you have nothing better

Step 4: Fill the blanks

For rows with a name and company but no email, there are three routes:

1. Pattern and verify. Work out the company's format (firstname.lastname@, f.lastname@) from a known address, build the email, then verify it. Accurate for small numbers, slow for hundreds.
2. Enrichment tools. Match on name plus domain, or on a LinkedIn URL. Fast, but check what the tool counts as "found".
3. Enrichment as a service. Send the file, get it back filled and verified.

Step 5: Check they still work there

The bigger cost in an old list isn't missing emails, it's people who've moved on. Their old address might not bounce straight away, which is worse: you think you're reaching them. Match your list against current profiles and update the title and company, or mark them as gone. If they moved to another company that fits your market, that's a new lead, not a dead one.

Step 6: Fill in what makes the list useful

Company headcount, industry and country let you split the list into segments that get different messages. A LinkedIn URL lets you check someone before you write to them.

What good looks like at the end

Before:  4,200 rows
  duplicates removed         -310
  left the company           -620 (180 re-found
                                   at new companies)
  emails found for blanks    +1,150
  invalid emails removed     -240
After:   3,180 usable, verified contacts

Fewer rows, many more replies. Then set up your sending properly: our guide on why cold emails go to spam covers domain setup, and buying a B2B email list covers the checks worth running on any new data you add.

Questions people ask

How often should I clean my contact list?

Before every major campaign, and at least quarterly for a list you email regularly.

Can I guess emails from the name and domain?

You can guess the pattern, but always verify before sending.

What's a catch-all address?

A domain that accepts any address, so a checker can't confirm the person exists. Send carefully and in small numbers.