Email warm-up tools for agencies are platforms that build sender reputation for multiple client domains simultaneously, providing multi-inbox management, per-client reporting, and scalable pricing. The top agency-grade options in 2026 are Warmy, Instantly, Smartlead, Mailreach, Folderly, and Warmbox, differing on pricing model, feature depth, and deliverability diagnostic capability.
Agencies managing multiple client domains deal with a deliverability problem at scale. Every new client domain needs warmup. Every campaign launch requires inbox health checks. Every reputation issue needs to be caught before it kills a client’s outreach. According to Validity’s 2025 Email Deliverability Benchmark Report, global inbox placement rates declined throughout 2024, making sender reputation management more critical than ever for high-volume senders.
The warmup tool that works for a solo SDR warming one inbox often fails an agency warming 30. Volume changes everything: pricing models, reporting requirements, multi-account access, and the ability to catch client reputation problems before they reach campaigns.
Warmy is an AI-driven email warmup and deliverability platform built specifically for this problem. It manages multi-domain warmup, client-level reporting, and domain health monitoring from a single agency dashboard. Not sure whether your domains are ready before your next campaign launch? Run a free Email Deliverability Test and see where your emails are landing right now.
What Agencies Need from a Warm-Up Tool
Before comparing tools, it helps to know which agency-specific features actually move the needle. These are the five requirements that separate agency-grade warmup tools from single-user products.
Bulk Multi-Inbox and Multi-Domain Management
Agencies do not warm up one inbox. They manage 10, 30, or 100. Any tool without a centralized dashboard for parallel warmup across client domains creates operational overhead that compounds with every new client onboarding. Look for tools with workspace-level separation so one client’s configuration does not interfere with another’s.
Per-Client Reporting
Clients want to see their inbox placement scores, domain health grades, and warmup progress. A tool with no per-client reporting forces your team to screenshot dashboards manually and produce reports by hand, which does not scale past a handful of accounts.
Seat and Volume Pricing
Per-inbox pricing models punish agencies for growing. A tool priced at $49 per inbox costs $4,900 per month at 100 inboxes. Flat-rate or tiered volume models keep costs predictable. Always run the math at your actual client volume, not at one inbox.
Centralized Health Dashboard
At agency scale, a reactive monitoring setup means you find out about a domain reputation crisis after it wrecks a client campaign. A centralized health dashboard with blacklist monitoring, SPF/DKIM/DMARC status, and spam rate tracking lets your team spot problems before campaigns launch.
API and Integrations
Agencies often need to connect warmup tools to their existing outreach stacks, CRM systems, or custom reporting pipelines. API access enables automation at scale: onboarding new client inboxes programmatically, pulling health data into dashboards, and triggering alerts without manual checks.
Quick Comparison Table
| Tool | Multi-Domain Mgmt | White-Label | Per-Inbox Price | Best For |
|---|---|---|---|---|
| Warmy | Yes (Workspace Mgmt) | No (discontinued) | Custom (book demo) | Full-suite deliverability + agency depth |
| Instantly | Yes (unlimited inboxes) | No | Flat from $37/mo | Budget-first agencies needing bundled outreach |
| Smartlead | Yes (sub-accounts) | Yes (Pro+ add-on) | From $39/mo flat | Agencies wanting white-label + outreach bundled |
| Mailreach | Limited | No | From $25/inbox/mo | B2B teams needing warmup + spam testing |
| Folderly | Limited | No | From $96/mailbox/mo | Enterprise diagnostics, mandatory 1-yr contract |
| Warmbox | Basic | No | From $15/inbox/mo (annual) | Budget warmup, 1–6 inboxes |
The 6 Best Email Warm-Up Tools for Agencies in 2026
1. Warmy
Warmy is the strongest full-suite option for agencies that need dedicated warmup infrastructure, per-client workspace management, and deep deliverability diagnostics under one roof.
Key Features
- Adeline AI warmup engine: adjusts each inbox’s warmup pace, sending volume, engagement patterns, and content based on real-time signals – no two mailboxes receive the same schedule. Learn more on the Warmy email warm-up product page.
- Workspace Management: separate, isolated environments per client with individual billing, access controls, warmup configurations, and reporting – team members see only the clients they manage.
- Domain Health Hub: domain-level deliverability dashboard showing health scores, spam rate trends, DNS authentication status (SPF, DKIM, DMARC, rDNS, MX), and blacklist monitoring across all managed domains in one view.
- Seed lists for Gmail, Outlook, and Yahoo: pre-verified seed list addresses let you run inbox placement tests before any live campaign, confirming actual landing destinations across major providers.
- Warmup preferences and customization: configure provider distribution, language (30+ languages), topic, temperature, and engagement patterns per inbox – the most granular warmup control in the category.
- Warmup With Clicks: when a warmup email lands, it gets opened, links get clicked, and a reply is generated – the Warmup With Clicks dashboard provides verifiable proof of engagement, not just volume statistics.
- Email Deliverability Test: free deliverability test shows real inbox placement across Gmail, Outlook, and Yahoo with a Smart Weekly Auto-Run option for continuous monitoring.
- Email Template Checker: scans email content for spam triggers before sending; also available as a free Chrome extension for pre-send checks directly from Gmail.
- Network: 1M+ active mailboxes; up to 5,000 warmup emails per day per inbox.
- Provider support: Gmail, Google Workspace, MS365, Outlook, Sendgrid, Yahoo, Mailgun, Custom SMTP, Brevo, Zoho, Amazon SES, GoHighLevel, and more.
- Email validation: 10,000 credits included on all paid plans; additional credits available at $0.007 each.
- Blacklist monitoring, SPF Record Generator, DMARC Generator, A/B deliverability testing, Inbox Academy (free masterclass), API access.
- Dedicated Customer Success Manager and dedicated deliverability expert on Custom plans.
Pro Tip: Warmy’s Agency Dashboard lets you give team members access to specific client mailboxes without sharing your main account login, eliminating the security and accountability problems that come with shared credentials.
Best for: Agencies that want dedicated warmup infrastructure with deep deliverability diagnostics, multi-domain management, and a single dashboard for all client inboxes.
Pros and Cons
| Pros | Cons |
|---|---|
| Dedicated Workspace Management per client | White-label reporting discontinued |
| Adeline AI adapts warmup per inbox automatically | Custom pricing requires a demo to get exact costs |
| 1M+ active mailbox network; real engagement signals | Per-inbox pricing scales up at large volume |
| Warmup With Clicks provides verifiable proof of engagement | Advanced customization locked to higher tiers |
| Deepest deliverability feature set in category | |
| Dedicated CSM + deliverability expert on Custom plans | |
| Rated 4.8 on G2 (498 reviews) |
Pricing
Warmy has moved to custom pricing in 2026. Previously, published plans ranged from $49/month (1 mailbox) to $429/month (20 mailboxes). A 7-day free trial is available with no credit card required.
| Plan | Price | Key Limits |
|---|---|---|
| Starter | ~$49/mo | 1 mailbox, 100 warmup emails/day |
| Business | ~$189/mo | Up to 5 mailboxes, 200 warmup emails/day |
| Premium | ~$429/mo | Up to 20 mailboxes, 800 warmup emails/day |
| Custom / Agency | Contact for pricing | 50+ mailboxes, dedicated CSM |
Rating: 4.8/5 on G2 (498 reviews)
2. Instantly
Instantly bundles unlimited email accounts and unlimited warmup into every outreach plan, making it the most cost-efficient option for agencies running high-volume cold email at flat-rate pricing.
Key Features
- Unlimited email account connections and unlimited warmup included on every Outreach plan – pricing scales by email volume and contact storage, not inbox count.
- Private warmup network of 4.2M+ accounts generating realistic engagement signals.
- Unibox: unified reply inbox consolidating responses from all connected mailboxes into one view (Hypergrowth plan and above).
- Cold email sequencing, A/B testing, and inbox rotation built into the same platform – no separate warmup tool needed.
- SISR (Server and IP Sharding and Rotation) on Light Speed tier for high-volume deliverability protection.
- No white-label client portals at any tier; workspace management functions as campaign-folder organization, not true client isolation.
Best for: Agencies managing cold email outreach for clients who want warmup, sequencing, and a unified reply inbox in a single platform without per-inbox pricing.
Pros and Cons
| Pros | Cons |
|---|---|
| Unlimited inboxes + warmup on all plans | No white-label client portals at any tier |
| Flat monthly pricing – scales without per-inbox fees | Warmup is not a dedicated standalone product |
| Hypergrowth plan ($97/mo) covers most agency needs | Full stack requires stacking Credits + CRM modules |
| Large 4.2M+ warmup network | Email-only; no native LinkedIn outreach |
Pricing
| Plan | Monthly Price | Inboxes | Warmup |
|---|---|---|---|
| Growth | $47/mo ($37 annual) | Unlimited | Unlimited |
| Hypergrowth | $97/mo ($77 annual) | Unlimited | Unlimited |
| Light Speed | $358/mo ($286 annual) | Unlimited | Unlimited |
Rating: 4.8/5 on G2
3. Smartlead
Smartlead is purpose-built for agency cold email infrastructure, with unlimited mailboxes, white-label client portals (the only tool in this list that still offers white-label), and a full API on its higher tiers.
Key Features
- Unlimited mailbox connections and unlimited warmup on every plan; pricing based on active leads and monthly send volume, not inbox count.
- Sub-account structure: each client gets an isolated workspace with its own billing, API token, reply queue, and optional white-label dashboard.
- White-label client portals available as a $29/month add-on from Pro tier upward; Unlimited Prime includes three workspaces – the only tool in this comparison offering white-label reporting.
- Master Inbox consolidates replies from all connected mailboxes with custom reply categories, webhooks to Slack and CRM systems, and team-level assignment.
- SmartDelivery add-on for pre-send inbox placement testing across major providers ($49 to $599/month depending on volume).
- Full API and webhooks on Pro and above for custom automation pipelines.
Best for: Agencies that need white-label client portals, sub-account isolation, API access, and bundled warmup with outreach sequencing.
Pros and Cons
| Pros | Cons |
|---|---|
| Only tool in this list offering white-label portals | Steeper learning curve than Instantly |
| True sub-account isolation per client | Deliverability testing is a paid add-on |
| API + webhooks on Pro and above | White-label requires $29/client/mo add-on on top of plan |
| Unlimited mailboxes + warmup on all plans | Email-only natively; no LinkedIn sequencing |
Pricing
| Plan | Monthly Price | Active Leads | White-Label |
|---|---|---|---|
| Base | $39/mo | 2,000 | No |
| Pro | $94/mo | 30,000 | Add-on ($29/client/mo) |
| Unlimited Smart | $174/mo | Unlimited | Add-on |
| Unlimited Prime | $379/mo | Unlimited | 3 included |
Rating: 4.5/5 on G2
4. Mailreach
Mailreach pairs automated inbox warming with built-in spam testing in one subscription, making it the strongest dedicated tool for agencies that need deliverability diagnostics alongside warmup.
Key Features
- Automated warmup via a real Google Workspace and Microsoft 365 inbox network with human-like content patterns and 50%+ reply rates on every plan.
- Built-in spam test layer: unique ID placement tracking showing where emails land across 30+ real inboxes at Gmail, Outlook, Yahoo, and other providers.
- 100 warmup emails per day per inbox on all plans; at least 20 spam test credits included per plan.
- DNS health checks: SPF, DKIM, DMARC, blacklist monitoring, and reputation tracking dashboard per inbox.
- Slack/webhook alerts for deliverability events and spam test results.
- Warmup API for programmatic inbox onboarding and health data retrieval.
- Tag-based inbox organization and single overview page across all client mailboxes.
- No free trial for warmup – you pay from day one; no outreach sequencing or white-label reporting.
Best for: B2B agencies and deliverability specialists who want dedicated warmup with built-in spam placement testing and DNS diagnostics, without an outreach platform bundled in.
Pros and Cons
| Pros | Cons |
|---|---|
| Warmup + spam testing included in every plan | No free trial – paid commitment from day one |
| Real Google Workspace / MS365 warmup network | Per-mailbox pricing scales poorly at 50+ inboxes |
| 50%+ reply rates on every plan – no upgrade needed | No outreach sequencing or client workspace isolation |
| Warmup API for programmatic multi-inbox management | Billing/cancellation complaints on Trustpilot |
Pricing
| Mailboxes | Per Mailbox/Month | Notes |
|---|---|---|
| 1–5 mailboxes | $25/mo each | Spam test credits included; no free trial |
| 6–20 mailboxes | ~$20/mo each | Annual billing saves ~20% |
| 21–50 mailboxes | ~$18/mo each | Contact for exact quote |
| 51+ mailboxes | ~$15–16/mo each | Custom / agency pricing available |
Rating: 4.7/5 on G2
5. Folderly
Folderly is an enterprise-grade deliverability suite combining automated warmup, spam trigger analysis, and IP reputation monitoring – but requires a mandatory one-year contract and charges separately for inbox placement testing.
Key Features
- Automated per-mailbox warmup running continuously in the background; AI adjusts behavior based on daily deliverability signals.
- Spam trigger detection: identifies content patterns flagging filters before campaigns go live, with AI content suggestions.
- IP reputation monitoring with real-time alerts via Pulse (free standalone tool); fires through Email, Slack, and SMS.
- Inbox Insights (separate paid add-on at $79/mo or $799/year): pre-send placement testing across Gmail, Outlook, and Yahoo only – does not cover Zoho or other providers.
- DNS health checks, blacklist monitoring, and domain health dashboard included in core plan.
- SOC 2 and ISO 27001 compliance documentation available – key differentiator for enterprise buyers.
- Mandatory one-year commitment on warmup plans – no monthly billing option for core product.
- Free trial available before committing; no agency workspace isolation or white-label reporting.
Pro Tip: Multiple verified users report a known automation bug where Folderly sent tens of thousands of warmup emails overnight without warning, destroying domain reputation. Monitor your sending volume closely in the first weeks, and verify the bug has been addressed before committing to an annual contract.
Best for: Enterprise agencies with fewer than 10 high-value client mailboxes where compliance requirements (SOC 2), DNS hand-holding, and comprehensive spam diagnostics justify the premium per-mailbox cost and annual lock-in.
Pros and Cons
| Pros | Cons |
|---|---|
| Most comprehensive spam diagnostics in category | Mandatory one-year contract – no monthly billing |
| IP reputation monitoring + real-time Pulse alerts | Inbox placement testing is a separate paid add-on ($79/mo) |
| SOC 2 and ISO 27001 compliance documentation | Placement testing covers Gmail/Outlook/Yahoo only |
| AI adjusts warmup based on daily deliverability signals | Known automation bug sent 42,000+ emails overnight for some users |
| Free trial available before annual commitment | No agency workspaces, no white-label |
Pricing
| Product | Price | Notes |
|---|---|---|
| Warmup (1–9 mailboxes) | $96/mailbox/mo (annual) | Mandatory 1-year contract; ~$120/mo without annual |
| Warmup (10–24 mailboxes) | ~$90/mailbox/mo (annual) | Volume discount tier |
| Warmup (25+ mailboxes) | ~$50–70/mailbox/mo | Contact for custom pricing |
| Inbox Insights (placement testing) | $79/mo or $799/yr | Separate add-on; not included in warmup plan |
| Pulse (spam monitoring) | Free | Standalone free tool |
Rating: 4.8/5 on G2 (101 reviews)
6. Warmbox
Warmbox is an accessible standalone warm-up tool for small teams, offering four warmup recipe types and a 35,000+ inbox network – but lacks spam placement testing, email content scanning, and has no independent verified reviews on G2, Capterra, or Trustpilot.
Key Features
- Four warmup recipe options: Grow Progressive, Flat, Randomized, and Custom – more scheduling granularity than most budget tools.
- Network of 35,000+ real inboxes across 100+ countries with GPT-4-powered email generation and auto-removal from spam.
- Supports Gmail, Outlook 365, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Mailgun, Amazon SES, and custom SMTP.
- Deliverability monitoring dashboard tracking inbox placement, spam score, reply rate, and daily volume.
- Free blacklist checker and DNS/SPF/DKIM/DMARC checker available to all users.
- No spam placement testing, no email content scanning for spam triggers, no API access.
- No free trial – paid plans only; team member seats are charged separately (a cost that adds up for agency use).
- No verified listings on G2, Capterra, or Trustpilot – evaluation relies on scattered Product Hunt and Reddit feedback.
Pro Tip: Warmbox’s default daily volume on the Start-up plan is 250 emails across 3 inboxes (~83/inbox/day), which exceeds the recommended safe warmup rate of 50 emails/day per inbox. Manually cap each inbox to 40–50 emails/day, especially on domains under 6 months old.
Best for: Solo senders or small agencies warming 1 to 3 inboxes who want simple automated warmup with scheduling control and do not need deliverability diagnostics or client workspace management.
Pros and Cons
| Pros | Cons |
|---|---|
| 4 warmup recipe types for fine scheduling control | No free trial – paid commitment from day one |
| 35,000+ inbox network with GPT-4 content generation | No spam placement testing or content scanning |
| Free blacklist + DNS checker for all users | No G2/Capterra/Trustpilot reviews to validate claims |
| Supports wide range of ESPs including custom SMTP | Default daily volume too high for new domains |
| Extra charge for team member seats | |
| No API access or client workspace management |
Pricing
| Plan | Annual Price | Monthly Price | Inboxes |
|---|---|---|---|
| Solo | $15/mo | $19/mo | 1 inbox, 50 emails/day |
| Start-up | $69/mo | $79/mo | 3 inboxes, 250 emails/day total |
| Growth | $139/mo | $159/mo | 6 inboxes, 500 emails/day total |
| Custom | Contact sales | Contact sales | 10+ inboxes |
Rating: No verified G2/Capterra/Trustpilot listings as of June 2026
How to Choose Based on Client Volu
Solo Consultants and Micro-Agencies (1–5 Client Domains)
Warmbox ($15/mo annual) covers basic warming at this scale. If you need deliverability diagnostics alongside warmup, Mailreach ($25/inbox/mo) gives you spam testing and DNS health checks in one subscription with no upgrade required – the $10/inbox gap buys you meaningful diagnostic depth that Warmbox does not include.
Growing Agencies (5–20 Client Domains)
This is where flat-rate platforms start winning on economics. Instantly’s Hypergrowth plan at $97/month covers unlimited inboxes, warmup, and sequencing. For agencies that want dedicated warmup depth without bundling outreach, Warmy’s custom agency plans scale pricing with inbox count and include the strongest feature set in the category. For deeper guidance on managing warmup across many client inboxes, see the Warmy guide to warming up inboxes at scale.
Established Agencies (20–50+ Client Domains)
At this scale, per-inbox pricing models become cost-prohibitive. Agencies that need white-label client portals should go with Smartlead, the only tool in this list that still offers white-label reporting. Agencies prioritizing the deepest warmup infrastructure and diagnostics should go with Warmy. To understand how Warmy compares at the feature level, see the Warmy feature comparison guide.
Enterprise Agencies
Folderly is the only tool in this list with SOC 2 and ISO 27001 compliance documentation and IP reputation diagnostics, but the mandatory one-year contract and known automation risk require careful evaluation. Warmy’s Custom plan includes a dedicated Customer Success Manager and a dedicated deliverability expert, providing a consulting layer at scale without the annual lock-in.
Check Your Campaign Readiness
Before your next client campaign goes live, verify that every domain in your stack is ready to send. Warmy’s free Email Template Checker scans email content for spam triggers before sending, so you know your client’s emails will land where they need to.
Conclusion
The best warm-up tool for agencies in 2026 depends on your client volume, your pricing tolerance, and whether you need warmup only or warmup plus outreach.
For agencies that want the deepest warmup feature set with agency-specific infrastructure, Workspace Management, and a dedicated deliverability expert on every account, Warmy is the strongest standalone option. For agencies that specifically need white-label client portals, Smartlead is the only tool in this comparison that still offers them. For agencies that want unlimited inboxes at the lowest flat-rate price with bundled outreach, Instantly keeps costs predictable. As Warmy’s Workspace Management feature release explains, the agencies that protect client pipelines most effectively are the ones that treat deliverability as continuous infrastructure, not a pre-campaign checklist item.
Ready to protect your agency’s sender reputation at scale? Book a demo and see Warmy’s agency dashboard in action.
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