Updated: September 04, 2025

Quick verdict: Instantly vs Lemlist for agency deliverability

For growing agencies, Instantly is built to maximize deliverability and cost control: flat-fee-by-volume pricing, unlimited sending accounts, a 4.2M+ warm-up network with inbox placement tests, and DFY/assisted setup. It also includes an AI sequence and copy generator, a 450M+ contact database, and a Unibox with AI tools. Best for teams prioritizing scale and deliverability.

Lemlist is better when you need creative, multichannel sequences and are one man band setup. Pricing is per user, with five mailboxes included per user (on Expert plan) and additional mailboxes at €9 per email per month. It includes Lemwarm for built-in warm-up, visual personalization (images and video), a 450M+ contact database, and a unified inbox. Watch-outs are the per-seat costs and mailbox limits unless you pay for extras.

Deliverability deep dive: What agencies need to know

1 in 6 emails on average don't reach the inbox. Your client results depend largely on one core metric: inbox placement. Deliverability for your agency is table stakes. Making your choice of cold email platform a mission-critical decision.

Key deliverability factors for high-volume outreach

To consistently land in the inbox at scale, your outreach must pass the checks run by email service providers like Google and Microsoft. The core technical pillars are:

• SPF (Sender Policy Framework): An authentication record that prevents spammers from sending messages on behalf of your domain.
• DKIM (DomainKeys Identified Mail): Adds a digital signature to emails, allowing the receiving server to verify the message is authentic and was not altered.
• DMARC (Domain-based Message Authentication, Reporting & Conformance): Tells receiving servers what to do with emails that fail SPF or DKIM checks.

Beyond these technical basics, sender reputation is your domain's "credit score," built over time through consistent, positive sending behavior. A gradual warm-up process for new email accounts is essential to build this trust.

How Instantly approaches deliverability

Instantly was built with a deliverability-first architecture for agency scale. The platform addresses the core challenges of high-volume sending with a multi-layered approach:

• Unlimited sending accounts: A flat-fee model allows you to connect unlimited email accounts. This lets you spread sending volume across many inboxes, protecting the reputation of each domain.
• Large warm-up network: Instantly uses a network of 4.2M+ real email accounts to automatically warm up your sending inboxes. The system simulates human-like conversations, opening emails, replying, and marking messages as important. This helps to build a positive sender reputation before you even launch a campaign.
• Specialized deliverability engine: Instantly's Server & IP Sharding and Rotation (SISR) system isolates campaigns on dedicated server and IP pools. If an IP address is flagged, it's automatically swapped out, preventing one client's campaign from affecting another's performance.

How Lemlist approaches deliverability

• Small to Midsized network: Lemlist's deliverability strategy centers on its warm-up tool, lemwarm. This tool connects users' inboxes into a peer-to-peer network of roughly 20K users to exchange warm-up emails. It gradually increases sending volume for new accounts and provides a deliverability score to monitor health.
• DIY Email Provider Checks: Lemlist requires users to follow best practices for setting up SPF, DKIM, and DMARC records. The platform does not offer the same architectural safeguards as Instantly, such as unlimited accounts for load balancing or isolated IP pools. This places more of the technical burden of reputation management on the agency, which can be a drag.

Feature showdown: Instantly vs Lemlist for agency operations

While deliverability is the foundation, an agency's daily operations depend on a wider set of features. Here’s how the two platforms compare on the tools across the board:

Email warm-up & sender reputation management

The difference in scale is significant. Instantly's warm-up network of over 4.2M accounts is substantially larger than Lemlist's 20K+ user network. For an agency managing dozens of client domains simultaneously, Instantly's capacity ensures all accounts can be warmed up effectively and in parallel. Instantly’s automated IP rotation provides an additional layer of protection that is critical for maintaining reputation across a diverse client base.

Verdict for Agencies: Instantly offers a more comprehensive and scalable solution for warm-up and reputation management.

AI personalization & sequence generation

Both platforms use AI to help write email copy. Lemlist's AI can assist with copywriting within its sequence builder. Instantly goes a step further with an AI-powered engine that can generate entire personalized sequences based on your value propositions and prospect data. This allows agencies to create highly relevant outreach campaigns in minutes.

Verdict for Agencies: Instantly provides a more advanced and efficient approach to AI personalization for agencies.

Lead sourcing & verification

Every successful cold email outreach strategy starts with a high-quality list. Instantly includes SuperSearch, an integrated B2B lead database with over 450M+ verified contacts. This allows you to find and enrich leads directly within the platform. Lemlist also provides access to a 450M+ contact database on its Email Pro plan. Both platforms include email verification to reduce bounce rates.

Verdict for Agencies: Instantly's integrated SuperSearch offers a more streamlined lead sourcing workflow.

Unified inbox & reply management

Managing replies from hundreds of campaigns across dozens of clients is a major operational challenge. Instantly's Unibox centralizes all replies from all connected sending accounts into a single dashboard. Its AI Inbox Manager helps categorize responses to streamline follow-ups. Lemlist offers a "Chat" feature that unifies interactions per lead, which is useful for tracking conversations but can be less efficient for managing high volumes of new replies across all campaigns.

Verdict for Agencies: Instantly's Unibox provides a more efficient solution for high-volume reply management.

CRM integrations & workflow automation

If you want speed, scale, and low ops overhead, to integrate your CRM into your outreach workflows Instantly is a great fit: straightforward wiring into HubSpot/Pipedrive with practical automation surfaces (Zapier triggers, webhooks, API) that make high-volume routing, updates and developer customisation easy without constant babysitting. Lemlist is a capable alternative with deep native CRM object coverage across HubSpot, Pipedrive, and Salesforce while also supporting creative features.

Verdict for agencies: Default to Instantly for predictable, high-throughput campaign ops. Consider Lemlist only if you explicitly need its visual features and can justify the per-seat trade-offs.

Making the choice: A deliverability-first recommendation for agencies

For agency owners, the decision comes down to your core business model. If your growth is tied to delivering consistent cold email results for an expanding client roster, your platform must prioritize deliverability and cost-effective scale above all else.

While Lemlist is a competent tool for multichannel outreach, its per-seat pricing and smaller-scale deliverability infrastructure create a ceiling for agency growth. Based on its architecture, built on unlimited accounts, a large (4.2M+) warm-up network, and a predictable flat fee, Instantly is designed to break through that ceiling.

Start your free trial of Instantly to experience the power of unlimited accounts and deliverability firsthand.

Frequently Asked Questions (FAQs)

How many sending accounts can I connect to Instantly vs. Lemlist? Instantly allows unlimited sending accounts on its core plans. Lemlist's Email Pro plan allows up to 5 sending addresses per seat, requiring you to purchase more seats to add more inboxes.

What is the size of each platform's warm-up network? Instantly's warm-up network includes over 4.2M million active email accounts. Lemlist's lemwarm network consists of over 20,000 users.

What is the starting price for each platform? Instantly's Growth plan starts at $37/month for unlimited accounts. Lemlist's Email Pro plan starts at $69/user/month.

Does Instantly offer multichannel outreach like Lemlist? No. Instantly is focused on being a best-in-class platform for cold email outreach. Lemlist's core strength is its integrated multichannel sequences that include email, LinkedIn, and calls.