Email WarmupBest Smartlead Alternatives for B2B Cold Email Deliverability in 2025Comparing Smartlead to MailReach, Folderly, Lemwarm, and others? This 2025 guide breaks down warmup tools built for B2B deliverability like real inbox networks, spam placement tests, and Outlook/Gmail support.
.webp)
If you’re using Smartlead for cold outreach, you’ve likely seen issues Smartlead can’t help you fix — emails hitting spam, reply rates dropping, and no clear reason why.
While the platform offers unlimited sending, automation, and built-in warmup, there’s no spam placement tracking, no diagnostics, and no visibility into inbox quality or reputation trends.
That’s not a small gap, especially when 48% of senders cite spam-folder hits as their top deliverability concern.
This guide compares Smartlead with five tools built specifically for B2B deliverability. For each, you’ll see:
If you’re rethinking your Smartlead setup or want more control over inbox placement, this breakdown will help you choose the right alternative.
On paper, Smartlead’s unlimited warmup sounds like a win for cold outreach teams . But in practice, “unlimited” usually means uncontrolled activity across unknown inboxes.
Without insight into inbox quality, placement results, or provider-specific behavior, Smartlead’s volume comes at the cost of visibility, leaving teams blind to deliverability damage until it's too late.
Here’s where Smartlead falls short for teams running B2B outreach at scale.
Smartlead treats warmup as an add-on rather than a dedicated product. Its focus is on campaign automation and sending volume, not on deliverability precision.
As a result, warmup lacks the control, depth, and monitoring capabilities needed for sender reputation management, such as placement tracking, inbox-level diagnostics, or alerts when sender reputation declines.
Smartlead’s warmup network is peer-based, but because it attracts a high volume of cheap, unlimited users, its inbox pool is saturated with Custom SMTP setups, and fewer Google Workspace and Outlook 365 accounts.
That’s a serious issue for B2B deliverability. Positive interactions from Microsoft and Google inboxes are what actually build sender reputation. Custom SMTP inboxes don’t influence reputation scores the same way and if they dominate the warmup network, you’re not training the inbox providers that matter.
Most peer-based warmup tools (including Smartlead and Instantly) allow any setup to join the pool. But when the network is skewed toward low-quality senders using Custom SMTP, it dilutes the trust signals you’re trying to send especially if you're targeting Gmail or Outlook recipients.
While Gmail-based sending may perform reasonably, some users have reported inconsistent performance when warming Microsoft inboxes. These issues are particularly problematic for B2B teams, which often rely heavily on Microsoft inboxes for prospecting and client communication.
Smartlead does not offer Outlook-specific diagnostics, testing, or warmup, leaving B2B senders exposed on one of their most critical email channels..
Smartlead doesn’t offer reputation trend monitoring, inbox placement tracking, or automated alerts when something breaks or your emails keep landing in spam.
Without guardrails like real-time alerts or placement diagnostics, teams lose the ability to course-correct in time. This makes it difficult to prevent issues like domain blacklisting, spam placement, or gradual reputation decay.
Most warm-up tools simulate engagement. MailReach is one of the few that actually shows where your emails land: with real inbox placement tests across Gmail, Outlook, and business domains.
What MailReach offers
MailReach automates warmup using a peer-to-peer network comprised of over 30,000 (mostly) Gmail and Outlook inboxes. Each one mimics real conversation patterns: sending, replying, recovering from spam, to gradually build sender trust with major providers.
Warmup activity runs automatically and cleans itself up post-send, so it doesn’t clutter your inbox or require manual cleanup.
Unlike most tools that simulate email checks or offer a single test inbox, MailReach's Spam Test sends your actual campaign email to a diverse set of 30+ Gmail, Outlook, and business inboxes.
This shows where your emails really land — in Primary, Promotions, Spam, or elsewhere — and helps you identify what’s hurting deliverability: content, setup, or sender rep.
👉 Unlike spam scores, which rely on static filters or rule-based checks, placement testing reflects how real inboxes treat your actual campaigns in live conditions.
You get per-inbox (so you can monitor your brand new inboxes and established ones separately) and per-domain Reputation Scores, warming performance data, inbox placement results, blacklist monitoring, and alerts when things drop.
MailReach is designed specifically for cold outreach, rather than bulk newsletters, e-commerce sends, or transactional flows. It mimics plain-text emails, short subject lines, and varied timing patterns to match real sender behavior.
Set up Slack or email alerts when deliverability drops, warmup issues arise, or inbox reputation degrades. You can also automate Spam Tests to run weekly, monitor performance over time, and respond proactively to prevent spam folder placement.
For agencies or ops teams managing dozens of inboxes, MailReach makes it easier to scale, with inbox tagging, batch settings, performance filters, and API access for automated oversight.
Mailwarm was one of the first standalone email warmup tools, but it hasn’t kept pace with the needs of modern B2B senders.
It uses a limited inbox network—not peer-based or provider-verified, and provides no visibility into performance, deliverability issues, or inbox quality. For B2B teams managing multiple domains or working at scale, it offers little control and no diagnostics, making it a poor fit for serious outbound operations.
Mailwarm sends, opens, replies to, and stars emails to simulate activity. You can configure the activity per inbox to gradually warm up a sender’s reputation.
The tool supports standard email services like Gmail and Outlook. However, it does not prioritize provider-specific behaviors or offer separate optimization for Microsoft inboxes.
Each inbox can send up to 50 warmup messages per day. While that may be sufficient for solo users, it doesn’t scale for agencies or growth teams managing dozens of inboxes.
You can’t see where your emails are landing: inbox, spam, or promotions, or identify why deliverability might be declining. If something breaks, you’re left guessing.
Mailwarm lacks features like bulk inbox management, reporting, or API access. It’s not built to support teams that run cold outreach at scale.
Mailwarm appears to be in maintenance mode, with no visible feature updates or product roadmap shared in recent years.
Folderly positions itself as a premium deliverability platform, combining software with expert support. It’s well-suited to enterprise teams focused on domain health, DNS setup, and long-term sender reputation.
But for B2B cold outreach teams that need fast setup, high volume, and inbox-level control , Folderly may feel less agile. Its warmup is bundled into a broader consulting-led service, and onboarding begins with a demo call, which can slow down leaner or high-velocity teams.
Folderly combines software with expert audits to assess DNS records, spam complaints, and domain configuration. This improves sender reputation over time, especially for teams starting from scratch or recovering from deliverability issues.
The platform provides a visual overview of reputation signals, blacklists, and DNS configuration. It's helpful for maintaining domain-level hygiene, but doesn’t offer inbox-specific diagnostics.
Folderly includes warmup as part of its larger deliverability suite, but it isn’t the platform’s core focus. You can’t configure warmup behavior per inbox or scale it across domains with control.
Folderly claims compatibility across major inbox types but doesn’t offer dedicated optimization or infrastructure visibility for Workspace or Office36.
You can’t create an account directly. All-access starts with a demo call, which slows down onboarding and doesn’t suit agile growth teams.
Folderly pricing typically starts at $120 per mailbox per month. This can become costly for companies managing 10–50+ inboxes, particularly if warm-up is the primary use case.
The platform focuses more on bulk senders and marketers than on lead gen teams. It lacks features tailored to the pacing, risks, and safeguards needed for high-volume outbound campaigns.
Folderly does not disclose the composition of its inbox network. Without visibility into provider types or engagement behavior, users can't assess whether the warmup builds trust with Gmail, Outlook, or other key ESPs.
Snov.io is built for lead generation, prospecting, and outreach campaigns, with warmups available on Pro-tier plans and above.
While it offers basic reply and open simulation, the warmup feature lacks visibility into inbox quality, reputation trends, and placement testing. For teams managing deliverability at scale, Snov.io’s approach may be too limited to prevent long-term issues like spam placement or domain decay.
Email warmup is included in Pro plans alongside CRM, prospecting features, and email campaign builder. It’s a helpful convenience for users already running full campaigns through Snov.io.
The warmup function creates engagement by automatically exchanging emails between inboxes, with subject and body personalization. This helps build some sender reputation but lacks deeper behavior modeling (like spam recovery or realistic reply variance).
For small teams looking to simplify their stack, Snov.io combines lead capture, verification, campaign management, and warm-up in one place.
Because warm-up is just one feature within a broader sales suite, there are no advanced settings, diagnostics, or analytics to monitor inbox performance or troubleshoot deliverability issues.
The platform is designed for sales reps and marketers, not deliverability specialists or agency leads. It’s not built to manage dozens of inboxes or monitor sender reputation trends.
As one of the earliest standalone warm-up tools, Lemwarm gained traction for being embedded into Lemlist’s cold outreach platform.
It introduced features like “warm your own templates” and “industry-based content”, which sound tailored, but can actually increase risk by triggering spam filters during warm-up.
With limited warmup volume, no inbox quality disclosure, and no spam testing, Lemwarm falls short for B2B teams that need scale, accuracy, and insight.
Lemwarm automatically sends, opens, and replies to emails between inboxes to simulate engagement and warm sender domains.
As part of Lemlist’s outreach platform, Lemwarm is easy to activate for existing users already running campaigns. Integration is smooth, with no extra setup.
The base plan only supports up to 40 warmup emails/day per inbox. This limits its usefulness for larger operations or agencies managing multiple domains.
Features like warming real templates or customizing warmup content increase the risk of hitting spam folders, especially during ramp-up. These aren’t best practices for deliverability.
There’s no visibility into the inbox network or where your emails actually land. You can’t evaluate effectiveness or diagnose performance drops.
Most warmup tools like Smartlead, Instantly, Lemwarm, and Snov.io prioritize convenience over deliverability depth. Folderly offers expertise, but its consulting-first model lacks agility. And Mailwarm, once innovative, hasn’t kept up with the complexity of modern inbox filtering.
MailReach stands apart by offering a platform designed for B2B teams who can’t afford to guess why deliverability is dropping.
It combines real warmup interactions across Google Workspace and Outlook inboxes with inbox placement testing, sender reputation tracking, diagnostic alerts, and performance monitoring, all designed to prevent spam issues before they happen.
If sender reputation is critical to your pipeline, MailReach gives you the control and visibility that other tools leave out.
Every email in spam equals to a lost potential customer. Start improving your inbox placement today with MailReach spam testing and warmup.
Following the rules isn’t enough—know where your emails land and what’s holding them back. Check your spam score with our free test, and improve deliverability with MailReach warmup.
Without the right warmup, your best campaigns are of no use. You can start by first testing your inbox placement and begin improving it today.
Best Smartlead Alternatives for B2B Cold Email Deliverability in 2025
Email Warmup Schedule to Optimize Deliverability (with a Proven Calendar)
Top 5 GMass Email Warm-Up Alternatives (2025)
5 Apollo Email Warmup Alternatives in 2025 (Since Apollo Dropped Theirs)
RBL Blacklists: What They Are, Why You’re Listed, and How to Get Delisted
