Smartlead vs Instantly vs Apollo for Scalable B2B Outbound

Feature comparison at a glance

What each platform actually does

Before comparing features, it helps to be clear on what job each tool is actually good at. Treating all three as interchangeable “cold email platforms” is where most setups go wrong.

Why Apollo isn’t built for high-volume sending

Apollo’s strength is its database — the search filters and contact verification are genuinely useful for finding the right people. The sending side is a different story. Apollo’s email sending limits and pricing are built around moderate outreach volume, not the thousands of emails per day that a scaled cold outbound operation needs.

There’s also a structural risk: if your CRM, your data source, and your sending domain all live in the same account, a deliverability problem on the sending side can affect the account you also rely on for prospecting. Keeping data extraction and sending separated avoids that overlap.

Instantly vs Smartlead for routing flexibility

Instantly popularized the unlimited-inbox model and its interface is genuinely easy to use. For one or two people managing a couple of domains, it does the job well.

The difference shows up once you try to connect either platform to Make.com and route reply data into a CRM like GoHighLevel. Instantly’s webhook payloads are usable but less flexible — when a prospect replies “not interested,” getting that exact reply status into a CRM pipeline stage via Instantly’s webhook can require extra parsing steps and tends to have less granular event data.

Smartlead’s API was built with this kind of routing in mind from the start. A “reply received” event fires a webhook with a clean, complete JSON payload — easy to parse in Make.com, easy to pass to an LLM for sentiment analysis, easy to route into the correct CRM pipeline stage automatically.

Where each one fits

• Choose Instantly if: you’re a solo operator or small team running one to two domains and don’t need deep CRM routing automation.
• Choose Smartlead if: you’re running multiple client campaigns, need webhook-driven routing into a CRM, or plan to scale past a few thousand sends a month.

Adding leads to Smartlead via API

Instead of exporting CSVs from Apollo and uploading them manually, a Make.com scenario can call the Apollo API on a schedule, map the returned fields, and POST them directly into a Smartlead campaign. This keeps your sending list updating automatically as new leads match your search criteria.

Here is the JSON structure Smartlead’s campaign API expects when adding a lead:

{
  "lead_list": [
    {
      "first_name": "{{1.first_name}}",
      "last_name": "{{1.last_name}}",
      "email": "{{1.email}}",
      "company_name": "{{1.organization_name}}",
      "custom_fields": {
        "apollo_id": "{{1.id}}",
        "industry": "{{1.industry_tag}}"
      }
    }
  ],
  "settings": {
    "ignore_global_block_list": false,
    "verify_email": true
  }
}

The {{1.field}} values are Make.com variable references — they pull directly from the previous module’s output (in this case, the Apollo API response), so each lead is mapped automatically without manual data entry.

Domain setup and warmup

The shared tracking domain problem

A domain can have perfect DNS records, a clean warmup history, and still see deliverability drop. One common cause that’s easy to miss: shared click-tracking infrastructure.

Most cold email platforms use a default tracking domain for open and click tracking — and by default, that domain is shared across many accounts on the platform. If another account using that same shared tracking domain gets flagged by Gmail’s sender guidelines or by Yahoo’s spam filters, links pointing through that shared domain can be affected — even though your own sending domain and content are fine.

The recommended setup

For small-scale outreach — one or two people, a handful of domains, low monthly volume — Instantly’s simplicity is a reasonable trade-off, and there’s no need to overbuild the stack.

For anything beyond that, the setup that holds up is: Apollo for finding and verifying contacts, Smartlead for sending at volume with proper domain separation and tracking isolation, and Make.com connecting the two so leads flow automatically without manual CSV work.

Frequently asked questions