Overview

SendScale Email Warmup is an email warmup service for teams and individuals preparing accounts for cold outreach. Its AI-driven exchanges and placement monitoring make it a fit for users who want warmup and campaign operations in one service, though the paid plans carry substantial annual commitments.

Key features

SendScale connects existing Google Workspace and Microsoft 365 inboxes through OAuth. Its warmup network comprises more than one million high-reputation inboxes; AI sends unique messages between accounts, opens and scrolls through them, and replies in human-style language. That simulated activity is central to the service’s approach to building sender reputation.

If a warmup message lands in spam, SendScale says it moves the message to the inbox, marks it important, and replies. The dashboard tracks daily sends and replies, spam-versus-inbox placement trends, and a readiness indicator. SendScale recommends 14 days of warmup for a new domain, with the dashboard indicating when it is complete. Warmup can continue at lower volume during campaigns, which may suit teams that want ongoing reputation maintenance rather than a one-time setup.

For multi-account workflows, SendScale can rotate connected accounts for load balancing and consolidate replies in its Master Smartbox. Growth tiers allow unlimited sending accounts and can mix Gmail and Outlook accounts. The service also includes spam monitoring. Privacy commitments include EU-only database server locations, industry-standard security measures, and promises not to sell or rent personal data or customer contact lists to third parties.

Pricing

The free plan costs 0.00 USD per free and includes pre-warmed inboxes, warmup tools, in-product conversational guidance, and campaign access. It provides a no-cost way to access the warmup workflow, but the plan details do not give sending or lead quotas, so users needing defined campaign capacity should compare the paid tiers.

Starter is $28/mo billed annually and includes 1,500 leads uploaded, 7,500 emails per month, and 200 credits. It is the lowest paid tier and is the clearest fit for smaller outreach operations with modest monthly volume. Growth is $76/mo billed annually, with 30,000 leads uploaded, 100,000 emails per month, and 500 credits; its unlimited sending accounts and mixed Gmail and Outlook support make it the stronger fit for teams managing multiple inboxes. Scale is $260/mo billed annually and raises capacity to 125,000 leads uploaded, 600,000 emails per month, and 900 credits, aimed at high-volume operations.

Each paid price is tied to annual billing, so the lower monthly figure comes with an annual commitment. General support tickets and priority support appear among the plan benefits, but tier assignments are not clear enough to distinguish by plan.

Platforms

SendScale is available on web and through an API. OAuth connections for Google Workspace and Microsoft 365 let users connect existing inboxes rather than switch providers.

Who it's for

SendScale names SDRs, agencies, founders, marketers, staffing agencies, growth teams, freelancers, and recruiters as intended users. Its combination of warmup, placement tracking, and campaign capacity is most relevant to cold-outreach users who need to manage account reputation alongside sending. Users who only need a small, tightly capped warmup allowance may prefer a service with explicit free-plan limits.

Pros and cons

Pros: The large warmup network, simulated replies, and automatic spam rescue cover several parts of the reputation-building workflow.
Pros: Placement trends and a readiness indicator give users visibility into warmup progress, while continued lower-volume warmup supports ongoing campaigns.
Pros: Growth supports unlimited sending accounts and mixed Gmail and Outlook inboxes, useful for teams distributing volume across accounts.
Cons: Paid plans are billed annually, which is a meaningful commitment for users still evaluating warmup tools.
Cons: The free plan’s campaign access is not paired with published lead or email quotas, making it harder to judge its practical capacity.
Cons: Support benefits do not map clearly to individual tiers, limiting plan-to-plan comparison for buyers who prioritize support.

Alternatives

Browse the Email Warmup Software directory to compare options. Consider Warmerly if Android access matters alongside web and API, or if its free plan’s campaign and lookup allowances suit your needs. TrulyInbox offers a free-forever plan capped at one account and 10 warmup emails per day, making it a more clearly bounded starting point. WarmEnvelopes is a web-based option with a free plan that covers up to 10 domains at four emails per day per domain.

darkzwarmer is a free alternative for Linux, macOS, Windows, and self-hosted environments. EmailWarmup is another web and API option, with its Starter plan offering three mailboxes and 100 warmup emails per day. InboxWarm.ai is a paid, web and API service with a free trial and mailbox-count-based pricing. Mailreach combines email warming with a spam tester in its All-In-One plan, including at least 20 spam test credits and up to 100 emails per day. MailStrike is a paid alternative with a free trial; its Growth plan includes up to six mailboxes, placement tests, and warming emails.

Verdict

Choose SendScale if you want warmup, placement visibility, and ongoing account activity tied to a cold-outreach workflow, especially across multiple inboxes. Its broad warmup network and campaign-scale Growth tier are the strongest reasons to choose it. Look elsewhere if you need clearly defined free-plan caps or want to avoid an annual commitment for paid access.

	SendScale Email Warmup	Warmbox
Free plan	Yes	No
Free trial	No	No
Paid from	$3,528/mo	—
Open source	No	No
Platforms	api, Web	Web
Free plan	Yes	No
Warmup network	private	—
Spam monitoring	Yes	—
Multiple mailboxes	Yes	—

SendScale Email Warmup vs Warmbox

SendScale Email Warmup

Warmbox