How I Use Clay to Build Cold Email Lead Lists That Actually Convert

Every top-performing campaign I've run has one thing in common: a clean, targeted, well-enriched lead list. Not a bloated Apollo export. Not a stale CRM dump. A list built with intent. And the tool that makes that possible, consistently, is Clay.

Most people in cold email haven't touched it. That's a mistake I want to help you avoid.

What Clay Actually Is

Clay is a single platform that pulls together dozens of outbound marketing tools under one roof. Instead of bouncing between Apollo, ZoomInfo, a verification tool, a spreadsheet cleaner, and your email sender, you do all of it inside Clay. It integrates with 70+ platforms natively, including Apollo, Airtable, Smartlead, BuiltWith, SimilarWeb, Semrush, HubSpot, Salesforce, and Apify. If a tool has API documentation and webhooks, Clay can talk to it.

The way I think about it: Clay is the operating system for outbound. Everything else is a plugin.

The Real Problem with Apollo and ZoomInfo Lists

Here's what kills most cold email campaigns before a single send: everybody is pulling from the same sources. You go to Apollo, filter by industry, location, and headcount, and so does every other agency, SDR, and founder targeting your niche. The data is saturated. The contacts are over-contacted. Response rates crater.

Clay fixes this two ways. First, it lets you pull from untapped data sources that most people don't know how to access. Second, it lets you cross-reference multiple databases in a single waterfall enrichment process, so you're not stuck with whatever Apollo happened to have on file.

When I tested this on a small list of nine fintech companies, the waterfall enrichment process found 9 out of 10 verified email addresses. Going to ZoomInfo or Apollo alone? You'd be lucky to get two or three.

Building a List Inside Clay: The Actual Workflow

Here's how I actually build a campaign list from scratch inside Clay.

Step 1: Find companies. I use Clay's "Find Companies" function, which pulls from LinkedIn data. I set filters for industry, description, location, and headcount. For a sample build in the video, I filtered for fintech companies in the US with 200-500 employees and got nine companies to work with. Small sample, but the process scales to thousands.

Step 2: Enrich the companies. This is where it gets interesting. I add enrichments like BuiltWith (to see what tech stack each company runs), SimilarWeb (monthly website traffic), and Semrush (competitor keywords, backlink data). If I'm selling SEO services, I want to know what keywords these companies are competing for before I write a single word of copy. Clay only charges you when it finds data, so if a source comes up empty, you pay nothing.

Step 3: Find the people. Once I have a qualified company list, I use Clay to find contacts at those companies. I filter by seniority (owner, partner, C-suite) and let the platform pull LinkedIn profiles and available contact data into a new table.

Step 4: Waterfall email enrichment and validation. Clay cross-checks multiple databases sequentially. If it can't find an email on the first source, it moves to the next, and the next. I run this alongside a validation tool like ZeroBounce, built directly into the waterfall. The result: a list of verified, deliverable emails. No bounce risk. No guessing.

Step 5: Clean and format. Clay has free built-in functions to normalize company names (stripping "Inc." and "LLC" so your emails don't read like a mail merge from 2009), format data fields, and flag anything that looks off.

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Personalization at Scale with Claygent

The feature I use most is Claygent, Clay's AI agent. This is where you stop sending emails that sound like templates and start sending emails that sound like you actually did your homework.

You give Claygent a prompt, and it scrapes the web, pulls from databases, and writes a personalized line for each contact. I've used it to pull recent podcast appearances, surface case studies from a prospect's website, and identify specific achievements from LinkedIn profiles. The AI can assist you in building the prompt if you're not technical. I'm not a developer, and I use this every day.

The quality of the output scales with the quality of your prompt. The more specific you are about what you want the AI to find and how you want it framed, the better the personalized lines get. A rough prompt gives you generic output. A tight prompt gives you something that reads like you spent 20 minutes on each prospect, when Clay spent 20 seconds.

Automated Workflows: The Full Pipeline in One Click

Beyond individual tables, Clay supports full workbooks, which are multi-step automated workflows. Here's one we run at BuzzLead: a webhook pulls company data scraped from Google Maps, Clay visits each website to confirm it's active, finds the business owner, writes a personalized message, validates the email, and pushes the entire cleaned list directly into Smartlead, our sending platform. One button. No human in the loop.

We send 300,000+ emails a month across our clients. That volume is only manageable because workflows like this replace what would otherwise require a full-time employee doing manual research. We've been running Clay for about a year and a half. The results are not close.

Key Takeaways

• Clay consolidates sourcing, enrichment, cleaning, validation, personalization, and deployment into one platform instead of five or six.

• Pulling from untapped data sources, rather than the same Apollo filters everyone uses, dramatically improves response rates because your contacts aren't being hammered by every other sender.

• Waterfall enrichment finds emails across multiple databases sequentially, typically recovering far more valid contacts than any single source alone.

• Claygent lets you personalize cold email copy at scale using AI, pulling from LinkedIn profiles, websites, case studies, and news without manual research.

• Automated workbooks can run the entire pipeline from lead sourcing to deployment with a single trigger.

• None of this matters if your emails don't land in the inbox. Deliverability is a separate problem that needs to be solved alongside list quality.

Frequently Asked Questions

What is Clay used for in cold email? Clay is an outbound marketing platform that integrates with 70+ tools to handle every stage of a cold email campaign: sourcing leads, enriching contact data, cleaning and formatting lists, validating emails, personalizing copy with AI, and pushing finished lists directly to your sending software.

How does waterfall enrichment work in Clay? Waterfall enrichment means Clay checks multiple data sources in sequence for each contact. If it can't find a verified email on the first database, it automatically checks the next one, and so on. This approach consistently recovers more valid email addresses than relying on a single source like Apollo or ZoomInfo.

What is Claygent and how does it help with personalization? Claygent is Clay's built-in AI agent. You give it a prompt describing what to find or write, and it scrapes websites, LinkedIn profiles, and other sources to generate personalized lines for each prospect. It's designed so non-technical users can create effective prompts without any coding knowledge.

Does Clay charge you if it can't find data? No. Clay only charges credits when it successfully returns data. If a source comes up empty for a given contact or company, you're not billed for that lookup.