How do they differ from ESPs like Mailchimp or SendGrid?

Cold email tools and traditional ESPs serve different purposes with different technical approaches.

Email Service Providers (ESPs):

Send through dedicated shared or dedicated IP infrastructure

Designed for marketing to opted-in subscriber lists

Bulk sending with high volume capabilities

HTML templates, design tools, A/B testing

Examples: Mailchimp, SendGrid, Klaviyo, HubSpot

Cold email tools:

Send through your actual mailboxes (Gmail, Outlook, Google Workspace)

Designed for outbound sales to prospects who haven't opted in

Lower volume, focused on mimicking human sending

Plain text emphasis, personalization tokens

Examples: Lemlist, Instantly, Smartlead

Key distinctions:

ESPs typically prohibit cold email in their terms of service

Cold tools connect to mailboxes rather than using APIs

ESPs handle millions of emails; cold tools optimize for thousands

Different compliance expectations and use cases

Using an ESP for cold email violates their terms and risks account termination. Use appropriate tools for your use case.