How to build a B2B lead list that doesn't bounce

The list decides more about a campaign than the copy does. A great email to the wrong people gets nothing, and a list full of dead addresses can damage a new domain in a day. Here's how I build lists that reach the right people and don't bounce.

Start with who, not where

Before opening any lead tool, write down who you're looking for in one sentence: the type of company, its size, where it is, and the job title of the person who'd say yes. "Marketing agencies of 10 to 50 people in the UK, founders and heads of growth." The tighter that sentence, the better everything downstream works.

Where the leads come from

• Lead databases such as Apollo or LinkedIn Sales Navigator let you filter by company type, size, location and title. They're the fastest way to a few thousand people who fit.
• Your own research, for small, high-value lists: conference speakers, companies hiring for a role you help with, businesses using a particular tool.
• Company domains you already have, from customers' competitors or a market map. Our domain extractor turns a messy list of emails or links into clean domains to search by.

When you have a name and a company but no email, the email permutator lists the likely addresses, which you then verify.

Clean the list

Lists from different sources overlap and arrive messy. Before anything else:

1. Remove duplicates, comparing emails without regard to capitals.
2. Trim stray spaces and fix names in capitals, so "Hi JANE" never goes out.
3. Keep one column per field: email, first name, last name, company, title, website.

The CSV list cleaner does all three in your browser.

Remove who you shouldn't email

Take out your customers, people who unsubscribed or asked not to be contacted, addresses that bounced before, and your competitors. Keep these in one suppression list and check every new list against it. The suppression list builder helps.

Verify every address

This is the step people skip and regret. Lists decay as people change jobs, and even a fresh export from a good database carries some dead addresses. Verification asks each address's mail server whether the mailbox exists, without sending an email.

Results come back in groups. Send to the valid ones. Remove invalid and disposable addresses. Be careful with "catch-all" addresses, where the server accepts everything so the mailbox can't be confirmed: send to them later, at low volume, after the confirmed ones. For a quick check of a few addresses, try the free email validator.

Keep bounces under 2%

If a campaign's bounce rate goes over 2%, stop and look at the list before sending more. A high bounce rate usually means an old source, a guessed address pattern, or a list nobody verified.

Verify right before sending

Verify when you're about to send, not when you build the list. A list verified three months ago has decayed since.

mailzy can do both halves: order a lead list built from your own Apollo or Sales Navigator search, verified and de-duplicated, or check any list with the Email Verifier, where your first checks are free and an unknown result is refunded. See lead lists and the Email Verifier.