Picking between MailReach, Lemwarm, Warmbox, and Folderly comes down to what you actually need: a standalone warm-up service that plugs into anything, a warm-up baked into your sending tool, a budget option for solo founders, or a full deliverability consultancy with software attached. None of them are bad. They are built for different buyers at different price points. This guide breaks down pricing, warm-up volume, network size, integrations, and the workflow tradeoff most comparisons skip.
Short answer: Pick MailReach if you want the most polished standalone warm-up and you already use a separate sending tool. Pick Lemwarm if you already pay for Lemlist and want it bundled. Pick Warmbox if you are a solo founder on a tight budget. Pick Folderly if deliverability problems are costing you real revenue and you want a fix-it consultancy, not a subscription. If you are running multi-channel outbound at scale, warm-up should not be a separate line item at all - bundle it inside your sending platform.
TL;DR - Quick Comparison
| Tool | Best for | Starting price | Network | Standalone or bundled |
|---|---|---|---|---|
| MailReach | Agencies and teams that want best-in-class warm-up separate from their sender | ~$25/mo per inbox (Starter) | Advertises 25,000+ real inboxes | Standalone |
| Lemwarm | Lemlist users who want warm-up bundled with sending | Included in Lemlist plans, ~$29/mo standalone | Built into Lemlist user base | Bundled with Lemlist |
| Warmbox | Solo founders, low budget, basic warm-up | ~$15/mo entry | Advertises 35,000+ inboxes | Standalone |
| Folderly | Companies with active deliverability damage and budget | ~$120/mo and up | Smaller network, heavier diagnostic layer | Standalone + consultancy |
| ACA | Anyone running real outbound who does not want a separate warm-up bill | Bundled with sending + rotation | N/A (different model) | Bundled |
What Email Warm-Up Actually Does
Before comparing tools, it helps to know what you are buying. A warm-up service connects your sending mailbox to a private network of other mailboxes. Those mailboxes send each other emails, open them, reply, and rescue messages from spam folders. This simulates the engagement signals that mailbox providers like Google and Microsoft use to score sender reputation.
The output is simple: your domain looks like a real human inbox having real conversations, not a cold sender blasting strangers. Done over weeks, this earns you the right to land in the primary inbox when you start real outreach.
All four tools do this same fundamental thing. The differences are in how they do it, who they sell to, and how they price it.
MailReach: The Standalone Standard
MailReach is widely considered the cleanest standalone warm-up product on the market. It connects to any SMTP-capable mailbox - Google Workspace, Microsoft 365, Zoho, Sendgrid, Mailgun, you name it. You point it at your inbox, set a daily volume target, and it ramps up gradually.
What sets MailReach apart is the level of polish: human-like timing patterns, varied subject lines, conversation threads with replies, and a deliverability dashboard that shows you exactly where your test emails land at each major provider. Their spam test feature sends a test email to dozens of seed accounts and reports inbox versus spam versus promotions placement in real time.
Pricing starts around $25 per inbox per month on the Starter tier, with a Full Access tier near $45 per inbox per month that unlocks higher daily volume and the full feature set. For agencies managing many client mailboxes, MailReach offers volume discounts.
Best for: Agencies and SDR teams running a separate sending platform (like Smartlead, Instantly, or a custom stack) who want the deliverability layer to be best-in-class and channel-agnostic.
Lemwarm: The Bundled Option
Lemwarm is the warm-up product from lempire, the same company that makes Lemlist. It can run as a standalone product, but the real reason people use it is that it is included in every Lemlist plan starting at 63 EUR per user per month on the annual Email Pro tier.
If you are already paying for Lemlist for outreach, you do not pay extra for warm-up. That is a meaningful saving. The downside: Lemwarm only really makes sense in the Lemlist ecosystem. As a standalone product at around $29 per month per inbox, it is competitive with MailReach on price but does not have the same depth of deliverability tooling.
Lemwarm's interface is simpler than MailReach's. You see a basic reputation score, daily warm-up activity, and a small set of placement insights. For most users this is enough. For agencies that want forensic-level deliverability data, it is light.
Best for: Existing Lemlist customers who want warm-up included in the subscription they already pay for.
Warmbox: The Budget Pick
Warmbox is the budget option in this comparison. Pricing starts around $15 per inbox per month, which makes it the cheapest of the four. It also advertises one of the larger warm-up networks (35,000+ inboxes per their site), though network size matters less than network quality.
Feature-wise, Warmbox covers the basics: gradual ramp-up, automated replies, spam folder rescue, and a simple reputation dashboard. What you do not get at this price point is the same level of placement testing, deliverability diagnostics, or human-like conversation patterns that MailReach offers.
For a solo founder warming up one or two inboxes for personal outreach, Warmbox is hard to beat on price. For an agency running 20+ client inboxes where any single deliverability issue costs real money, the savings may not be worth it.
Best for: Solo founders, freelancers, and anyone running low-volume outreach who needs warm-up but cannot justify $25 to $45 per inbox per month.
Folderly: The Deliverability Consultancy
Folderly is the odd one out. It is not really a peer of the other three - it is positioned as an enterprise deliverability solution with software, diagnostics, and human consultants attached. Pricing starts around $120 per month for the basic tier and climbs into four-figure monthly costs for enterprise plans with active deliverability remediation.
What you get with Folderly is a full deliverability audit, ongoing placement testing across providers, content and authentication analysis, and human experts who help you fix the underlying issues when warm-up alone is not enough. For a SaaS company whose product emails are landing in spam and costing them activations, Folderly's price tag makes sense.
For an outbound team that just needs warm-up, Folderly is overkill. You are paying for the consultancy layer, not just the software.
Best for: Companies with active deliverability damage where lost email is costing real revenue, and where a full audit plus ongoing remediation is worth four figures a month.
Side-by-Side Feature Comparison
| Feature | MailReach | Lemwarm | Warmbox | Folderly |
|---|---|---|---|---|
| Standalone product | Yes | Yes (also bundled) | Yes | Yes |
| Connects to any SMTP | Yes | Yes | Yes | Yes |
| Spam placement testing | Yes (strong) | Light | Light | Yes (strong) |
| Conversation threading | Yes | Yes | Yes | Yes |
| Daily volume ceiling | High (tiered) | Medium | Medium | High |
| Deliverability audit | Self-serve | Self-serve | Self-serve | Human-led |
| Native sending integration | No | Yes (Lemlist) | No | No |
| White-label for agencies | Limited | No | No | Custom |
| Multi-inbox dashboard | Yes | Yes | Yes | Yes |
Pricing Breakdown
Here is what you actually pay per inbox per month at entry tier, based on each vendor's public pricing page at the time of writing. Verify current pricing before committing - these tools update pricing frequently.
- MailReach: Starts around $25/inbox/mo (Starter), with Full Access near $45/inbox/mo. Volume discounts for agencies.
- Lemwarm: Around $29/inbox/mo standalone, or bundled with Lemlist starting at 63 EUR/user/mo annual on Email Pro.
- Warmbox: Starts around $15/inbox/mo on the entry tier.
- Folderly: Around $120/mo entry tier, with enterprise plans running significantly higher.
The hidden cost most teams miss: warm-up is a per-inbox subscription. If you run 10 inboxes across multiple secondary domains (typical for an agency sending 300-500 emails per day), your warm-up bill is your per-inbox price times 10. At MailReach Full Access that is around $450 per month just for warm-up - before you pay for the sending tool, the lead data, the email accounts themselves, and the domains.
Real cost reality check: An agency running 10 warmed inboxes for cold outreach typically pays $150 to $450 per month for warm-up alone, on top of $60 to $70 per month for Google Workspace inboxes, $100 to $200 per month for a sending tool, and the cost of secondary domains. Warm-up as a standalone line item adds up faster than most operators expect.
Network Size and Daily Volume
Warm-up vendors love to advertise network size: "35,000+ inboxes" or "50,000+ real users". Network size matters, but not in the way the marketing implies.
What actually matters is network quality: how many of those inboxes are at major providers (Gmail, Outlook, Yahoo) versus obscure ESPs, how active those inboxes are in real conversations, and how diverse the IP ranges are. A smaller, higher-quality network can outperform a bigger one that is full of inactive accounts.
All four tools also cap daily warm-up volume per inbox. Typical ceilings: 40 to 50 emails per day on entry tiers, scaling to 100+ on higher tiers. This matters because if you are sending 80 real cold emails per day from a warmed inbox, you want your warm-up activity to be at least that high - otherwise the warm-up signal is noise compared to your actual sending pattern.
In our experience, the difference between vendors at the 50-emails-per-day level is small. The differences show up at higher volumes and in placement testing depth.
Integrations and Sender Compatibility
All four tools support any SMTP-capable mailbox: Google Workspace, Microsoft 365, Zoho, custom IMAP, and most ESPs. None of them care which sending platform you use - warm-up runs in parallel to whatever else you do with the inbox.
The integration question that matters is whether warm-up coordinates with your sending volume. Most standalone tools do not. They run a fixed schedule regardless of how much real outreach you push through the same inbox. If you blast 100 cold emails on Tuesday, your warm-up tool keeps running its 30 daily simulated emails without adjusting. That can create a sending pattern (warm-up plus real outreach combined) that overshoots provider limits.
This is the workflow gap that most comparison posts skip.
Who Should Pick What
Pick MailReach when: you want the best standalone warm-up, you run a sending stack that is not Lemlist, and the per-inbox price is acceptable. Strong choice for agencies that take deliverability seriously.
Pick Lemwarm when: you already pay for Lemlist and want warm-up bundled. Do not buy it standalone unless you have a specific reason - MailReach is more polished at a similar price.
Pick Warmbox when: you are a solo founder or freelancer running one or two inboxes and you need a budget option. Acceptable for low-stakes warm-up. Not what you want for an agency at scale.
Pick Folderly when: your deliverability is already broken, lost email is costing real revenue, and you need a human-led audit and ongoing remediation - not just a warm-up subscription.
Pick none of them when: you are running real multi-channel outbound at scale and you do not want to pay a separate warm-up bill on top of every other tool.
The Bundled Alternative: Warm-Up Inside Your Sending Platform
Here is the workflow problem with every standalone warm-up tool: you are paying twice. Once for the sending platform that drives your campaigns, once for the warm-up service that protects the inboxes those campaigns send from. Two subscriptions, two dashboards, two reputation systems that do not talk to each other.
ACA takes a different approach. Warm-up runs inside the same platform that handles sending, inbox rotation, and reply management. The system knows how much real outreach is flowing through each inbox on a given day and adjusts warm-up activity accordingly. When real send volume is high, warm-up backs off so the inbox is not overloaded. When sending is paused, warm-up keeps running to maintain reputation baseline.
Inbox rotation is the second piece. Instead of warming five inboxes and hoping each survives a campaign, ACA rotates sending across a pool of warmed inboxes automatically. If one inbox shows reputation degradation, it gets pulled out of rotation and rested while the others keep producing. This is the operational layer that standalone warm-up tools do not handle - they warm the inbox, but it is on you to decide when to rotate it out.
For an agency running 6-channel outreach (LinkedIn, email, WhatsApp, Instagram, Telegram, SMS) across multiple clients, the bundled approach eliminates an entire vendor relationship and aligns warm-up with the actual sending pattern. The platform fee is flat regardless of how many inboxes you connect.
If you want to see how this works end-to-end, the ACA community on Skool runs through the full setup - warm-up, sending, rotation, and inbox management - in one place: skool.com/aca-xtreme.
Frequently Asked Questions
Do I still need warm-up if I bought aged domains?
Yes. Aged domains have a head start on reputation - they exist in WHOIS records, they may have light historical email activity - but they have no recent sending reputation specific to you. Warm-up builds that recent reputation. Skipping warm-up on an aged domain because you assume the age does the work is one of the fastest ways to torch a $200 domain.
Can I run multiple warm-up tools on the same inbox?
Technically yes, practically no. Running two warm-up services on one inbox doubles the simulated activity and creates patterns that look unnatural to mailbox providers. Pick one and let it run. The exception is if you are migrating between tools - run them in parallel for a week, then disconnect the old one.
How long until warm-up actually starts working?
Visible reputation lift typically takes 2 to 4 weeks of consistent warm-up activity before you can start real cold outreach safely. The first week is mostly the network learning your sending fingerprint. Weeks 2 to 4 build the engagement signals that providers use to score you. Anyone telling you they have a 3-day warm-up is selling theater, not deliverability.
Does the warm-up tool need to be in the same country as my mailbox?
No. The warm-up network is global by design - that diversity is part of what makes the engagement signals look natural. What does matter is that the network has enough activity at the major providers you are trying to reach (Gmail, Outlook, Yahoo) and that your real outreach targets a similar mix.
Is warm-up enough to fix bad deliverability on its own?
No. Warm-up is a reputation-building tool. It does not fix broken authentication (SPF, DKIM, DMARC), bad list hygiene, spammy content, or aggressive sending patterns. If you are landing in spam after a clean warm-up, the issue is upstream of the warm-up tool. This is where Folderly's consultancy model earns its price tag - they actually diagnose the root cause.
What happens when I cancel a warm-up subscription?
Your inbox stops receiving simulated engagement immediately. The reputation you built does not vanish overnight, but it decays over weeks if real outreach engagement does not replace it. Most operators run warm-up continuously as a baseline activity, not as a one-time setup phase.
Why does ACA not list a separate warm-up price?
Because warm-up is not a separate product in ACA - it is one capability inside the sending and rotation system. You connect inboxes, the platform handles ramp-up, rotation, and reply management together. The economics work because warm-up runs on infrastructure you are already paying for, not as a second vendor relationship.