8 Best Email Deliverability Tools for Cold Outreach in 2026
Struggling with emails going to spam? Discover the 8 best email deliverability tools in 2026 to warm up inboxes, monitor reputation, and land in the inbox.
Deliverability is the missing piece of your email strategy.
Even the most strategic campaigns fail if they get stuck in spam. Make sure your best work gets results. Run a free placement test to see where your emails are really going.
You’ve probably heard of Instantly, Lemwarm, and Smartlead.
Instantly’s great for scaling outreach, but doesn’t show where your emails actually land.
Smartlead offers inbox rotation, but no sender reputation tracking.
Lemwarm helps warm up new domains, but it lacks real-time alerts or visibility into spam folder issues.
Every tool solves a part of the problem. But when your entire pipeline depends on inbox placement, surface-level features won’t cut it.
In this guide, we’ve broken down the eight best email deliverability tools in 2026, focusing on the technical factors that actually improve old outreach performance:
High-trust warm-up networks
Real inbox placement testing
Domain/IP reputation tracking
Proactive alerts for fixable issues
Whether you’re managing 3 inboxes or 300, these tools help you avoid silent failures and keep cold emails landing where they should.
Top Email Deliverability Tools: A Quick Overview
Tool
Key Features
Free Trial
MailReach
Real Google/Office365 network, spam test with 30+ inboxes, alerts, API
Boost email deliverability with MailReach’s trusted warm-up and spam test network.
MailReach is designed specifically for B2B cold email senders who need high inbox placement at scale.
Unlike generic warm-up tools or all-in-one outreach platforms that give you a vague “10/10 spam score, MailReach is laser-focused on B2B deliverability. It provides warming and diagnostics both in one specialized solution. It warms your inbox using a network of 30,000+ real Google Workspace and Office 365 inboxes.
It tests your actual campaigns under real conditions, showing exactly where your emails land (such as Gmail inbox or Outlook spam). MailReach consistently outperforms cheaper tools that rely on superficial features or shared SMTP pools.
Key features
Warm-up using 30,000+ real Google Workspace + Office 365 inboxes (no burner domains)
Scale cold outreach fast using Instantly’s all-in-one warm-up and automation system.
If your goal is to send cold emails fast and at scale, Instantly gets you moving.
With built-in outreach, warm-up, inbox rotation, and AI steps, it’s great for teams who want one tool for everything.
But here’s the trade-off:
You get volume, not visibility. There’s no inbox placement testing, no real-time sender reputation tracking, and limited diagnostics when things go wrong.
Key features
Schedule, automate, and send cold email sequences using multiple inboxes
Run multichannel outreach by combining cold email with LinkedIn and Twitter steps in a single flow.
A/B test subject lines and message content across steps to find what converts best.
Keep outreach moving with automated bounce handling and sending pauses if deliverability drops.
Track open rates, replies, and an overall “reputation” score per inbox, though with limited visibility into why performance may dip.
What we like about Instantly
Supports automation and AI features like reply detection and personalization
Responsive support team and helpful chatbot
Strong integration options with tools like Slack, HubSpot, and Google Workspace
What to watch out for
Reporting is too basic and lacks deeper analytics
Some users report lag when managing large lists or complex sequences
Their network is filled with Custom SMTP and lacks Google Workspace and Office 365 inboxes
Ideal for
Growth marketers, startups, and agencies that want to launch and scale cold email campaigns quickly without juggling separate warm-up and outreach tools. Great for teams focused on speed and simplicity over diagnostic granularity.
Automate multi-inbox outreach and warm-up using Smartlead’s email infrastructure.
Smartlead is what you grab when you’re managing 50+ inboxes and want to automate outreach without breaking things.
It supports multi-inbox rotation, custom triggers, and AI personalization out of the box. Warm-up runs in the background, and you can plug it into CRMs or Slack with ease.
Smartlead shows inbox/spam placement, but this is not broken down per provider or tab, so it provides an overall health check rather than pinpoint troubleshooting.
Key features
Send multichannel cold outreach at scale with unlimited sender accounts and automatic inbox rotation to spread volume safely.
Use the built-in warm-up feature to gradually increase sending volume through human-like engagement and help protect new domains from early flags
Connect Smartlead to tools like HubSpot, Slack, Zapier, and Webhooks to automate lead handoffs or notifications
Set custom sending rules for time zones, days, or response-based triggers. You can pause a sequence automatically if a lead replies or meets certain criteria.
Access basic deliverability insights like open/reply rates and bounce stats.
What we like about Smartlead
Powerful API and webhook support for automation
Unified Master Inbox for managing replies across accounts
AI personalization and Spintax features help scale campaigns efficiently
What to watch out for
The reporting dashboard lacks deep customization and reply segmentation
Occasional bugs in the Master Inbox that require a refresh
Their network mostly consists of custom SMTP and lacks Google Workspace and Office 365 inboxes
They focus on cosmetic features like template warmup, which plays no role in boosting deliverability
Ideal for
Agencies and high-volume outreach teams managing dozens of inboxes that want everything under one roof without needing separate tools.
Improve sender reputation with Lemwarm’s geo-distributed warm-up system.
If you’re already using Lemlist for outreach, Lemwarm is the easiest add-on to keep your domains healthy.
It automates sending and replying to warm-up emails through a large network of real inboxes, so you can maintain domain reputation without extra manual work.
But Lemwarm won’t tell you if your emails actually land in Primary, Promotions, or Spam across major ISPs. You’ll see proxy metrics like deliverability scores and spam/bounce rate warnings, but not true placement data, so it’s best as a “set it and forget it” warm-up layer, not a full deliverability diagnostic tool.
Key features
Automate your warm-up with real, geo-distributed inboxes that simulate human-like conversations to build trust with email providers.
Monitor inbox health daily using a red/orange/green deliverability score that reflects key risk signals.
Run DNS checks to validate that SPF, DKIM, DMARC, MX, and tracking domains are configured correctly, so you don’t unknowingly tank deliverability.
Get notified if your domain appears on a blacklist, with suggested fixes to help you respond quickly.
Use a centralized dashboard to track sending trends, domain health, and inbox placement signals like spam rate and bounce volume.
What we like about Lemwarm
Uses geo-distributed, real email accounts (including Google and Microsoft), not low-quality SMTPs, which gives your warm-up signals more trust with ESPs.
Checks your SPF, DKIM, DMARC, MX, and tracking domain setup and flags issues that could hurt deliverability.
Alerts you if your domain or IP is listed, and provides next-step instructions, useful for staying ahead of reputation drops.
What to watch out for
Doesn’t offer granular sender reputation diagnostics or show if your real emails land in Primary, Promotions, or Spam.
While it can be used outside Lemlist, the UX and integrations are better when both are used together.
They place a lot of focus on cosmetic features like warmup by industry, which is a factor that Google and Office 365 do not look at when determining deliverability
Ideal for
Solo founders, startups, and agencies that already have an outreach tool and need a specialized warm-up system.
Strengthen deliverability with Warmup Inbox’s simple, low-maintenance warm-up engine.
If you just want a hands-off way to keep your sender reputation afloat, Warmup Inbox does the job. It hooks into a large network of real inboxes and runs automated, human-like exchanges to make your activity look natural.
The blind spot: it won’t tell you why deliverability drops. There’s no inbox placement testing, blacklist monitoring, or deeper diagnostics, so if something breaks, you’ll be guessing. You’ll need to pair it with a diagnostic tool like MailReach to see the full picture.
Key features
Sends 75 emails per day (on the basic plan) with simulated 25% reply rates to mimic real engagement.
If your warm-up emails land in spam, they’re automatically marked as “not spam” to help retrain inbox algorithms and improve placement.
Track your sender health with a simple dashboard that shows inbox vs spam delivery trends over time.
Get alerts if SPF, DKIM, or DMARC records aren’t configured correctly, though you’ll need to fix them manually.
Use a lightweight, distraction-free interface that’s ideal if you want a budget-friendly warm-up tool with no extra outreach features.
Upgrade plans offer options like warming in different languages and adjusting send schedules, but these are minor improvements rather than game-changers.
What we like about Warmup Inbox
Most users say it takes under 15 minutes from signup to active warm-up.
2,500+ real Gmail/Outlook accounts simulate authentic conversations.
Many reviews highlight quick, personal help from agents.
What to watch out for
You can’t see if emails land in Primary vs Promotions vs Spam.
Several users found billing unclear when managing multiple inboxes.
Ideal for
Solo founders, freelancers, or early-stage teams who want an affordable, hands-off way to warm up inboxes before launching outbound campaigns.
Ramp up deliverability at scale using Warmy.io’s high-volume warm-up automation.
If speed and scale are your priority, Warmy.io is built for it. Its top plan pushes up to 5,000 warm-up emails per day from a single inbox, enough to revive a burned domain fast or prep for massive send volumes.
That firepower makes it a fit for high-traffic ecommerce campaigns, but in B2B outreach, those numbers can raise red flags with providers. You get brute-force warm-up, not the subtle, diagnostic approach of a tool like MailReach.
Key features
Send test emails to see whether they land in the inbox or spam across multiple providers.
Validate your DNS setup (SPF, DKIM, DMARC, MX) to ensure email authentication is configured correctly before sending at scale.
Monitor domain health using the Deliverability Monitor dashboard, which surfaces basic deliverability signals and issues over time.
On higher-tier plans, you’ll get access to a dedicated deliverability expert who can offer strategic guidance, though this is more consultative than diagnostic.
Choose from three preset warm-up speeds depending on how quickly you want to ramp up sending volume, but note that these are generic templates and don’t adapt dynamically.
Optionally warm up inboxes in 30+ languages (e.g., Spanish, French, German), though this has minimal effect on actual deliverability if you're targeting English-speaking recipients.
What we like about Warmy.io
Very effective at warming up cold or brand-new domains. Users report significant improvements in sender reputation.
AI engine mimics real human engagement and gradually builds trust with inbox providers.
Compatible with Gmail, Outlook, Sendgrid, Mailchimp, and other major platforms.
What to watch out for
Dashboard performance can lag with larger datasets.
Some features, like language support or email content suggestions, may not materially affect deliverability.
Key deliverability features (like diagnostics or consulting) are gated behind custom pricing
Ideal for
Ecommerce brands, marketing teams, and high-volume senders who want a fully automated warm-up process with minimal manual intervention.
Pricing
Pricing is not publicly listed; prospective users must book a demo to receive a quote. They do offer a 7-day free trial.
7. Folderly
Resolve inbox placement issues with Folderly’s full-stack email diagnostics.
Folderly positions itself as a full deliverability repair service, not just a warmup tool. It runs daily placement tests, scans for spam triggers, checks domain/IP health, and flags blacklist issues—then works with you to fix them.
You have to factor in that it’s priced for hands-on support, so it makes the most sense if you’re dealing with ongoing, high-value deliverability problems, not scalable warm-up.
Key features
Send test emails and instantly see if you’re landing in the inbox, spam, or promotions tab across Gmail, Outlook, and other major providers.
Get alerts when your templates contain spammy words, broken links, or header issues that could tank your deliverability.
Track your domain and IP health in real time, SPF, DKIM, DMARC, blacklist status, bounce rates, and more, all in one place.
Let Folderly’s warm-up system run in the background to send and engage with emails through a controlled network that mimics natural sender behavior.
Receive deliverability alerts via email or Slack when things start to slip, so you can fix problems before campaigns suffer.
Integrate with your existing ESPs (like Gmail, Outlook, SendGrid) without needing to rework your entire workflow.
Use your dashboard to spot trends, monitor improvements, and make data-backed decisions to optimize inbox placement over time.
What we like about Folderly
Helps users identify specific words or structural issues causing spam flags.
Most reviewers find the platform easy to set up and monitor, even for non-technical users.
Offers DNS help, template validation, deliverability scoring, and placement analytics in one place.
What to watch out for
Warm-up is secondary. The core value lies in diagnostics and consulting.
Not ideal for fast-moving cold outreach teams that need scale, speed, or inbox-level control.
High pricing: $120/inbox/month with no free trial.
Slower feedback loop—fixes often rely on manual support rather than real-time alerts.
Some users report setup friction or DNS-related confusion.
Ideal for
Companies with persistent, high-stakes deliverability issues and not routine cold outreach. Folderly suits teams that prefer a consulting-style engagement over hands-on control.
Repair sender reputation using InboxAlly’s rich engagement warm-up simulation.
InboxAlly is for senders who want more than just warm-up volume. It opens, scrolls, clicks links, replies with natural text, and even rescues emails from spam or promotions. Best fit if you care about shaping engagement signals across Gmail, Outlook, and Yahoo, not just sending activity.
While powerful, InboxAlly is one of the most expensive tools on the list, with plans starting at $149/month per inbox, making a steep jump to $645/inbox/month for the very next tier.
Key features
InboxAlly will open your sent messages, scroll long emails, click links inside, mark them as important, move them out of spam or promotions, and reply with realistic messages, training mailbox providers with rich engagement signals.
Daily structured ramp‑up schedules tailored to your sender profile, Starter for new domains, Reputation Boost for established ones, or Reputation Repair for degraded accounts, helping you rebuild trust steadily.
Placement tracking that lets you monitor where every warm‑up email lands to track progress over time.
Customized sender profiles so you can adjust engagement ratios (open rate, replies, scroll depth), giving you more control over reputation-building behavior.
A rich reporting dashboard that shows inboxing percentages and broadcast history without needing to migrate platforms.
Especially useful for domains with severe spam placement issues.
What to watch out for
Signals like clicks and scrolls are cosmetic, not diagnostic, and may not be trusted by Gmail/Outlook if not from real professional inboxes
Doesn’t focus on core diagnostics like DNS issues, blacklist status, or spam placement testing for real campaigns
High pricing ($149+/month) may be hard to justify without deliverability transparency
Ideal for
Senders trying to rapidly recover damaged domains or simulate engagement at scale, though it’s best paired with a diagnostic tool if you want real visibility into what’s actually affecting deliverability.
Important things to consider when choosing an email deliverability tool
If your business relies on outbound email, especially cold outreach, the wrong tool can quietly sabotage your campaigns. Here are some practical things to keep in mind before making a decision.
Sender network quality
Check what kind of inboxes the tool uses for warm-up. Are they real Google Workspace or Microsoft 365 accounts, or just low-quality SMTPs? Tools that rely on generic SMTPs often fail to build meaningful trust with inbox providers, weakening your sender reputation over time.
Test realism
Many tools give you a basic spam score, but that’s not the same as seeing where your actual content lands. Look for a platform that lets you send a test email and track its placement across Gmail, Outlook, Yahoo, and others. That’s the only way to know if your campaigns are truly landing in inboxes or silently hitting spam.
Scale
If you’re managing more than a few inboxes, say, for a cold outreach team or an agency, you need software that can handle 50 or even 100+ inboxes without breaking down. That means a clean dashboard, inbox-specific insights, and batch-level controls that don’t require switching between accounts constantly.
Support
Deliverability isn’t static. It can tank overnight. When that happens, you don’t want to be stuck reading help docs.
Choose a tool that offers expert support, real-time alerts, or dedicated Slack channels. Quick, expert help can mean the difference between a minor fix and a week of lost revenue.
Pricing transparency
Some tools advertise low monthly rates but hide key features behind expensive tiers or throttle you based on email volume. A good deliverability platform should be upfront about what you get per inbox, no hidden limits, no need to “book a demo” just to see a price.
If you run cold email at scale, you’ve likely seen it happen. Open rates fall, replies slow down, and nothing in your copy explains why. You test new subject lines, switch up your send times, and rotate domains. Only for emails marked as sent but never actually seen.
Strong deliverability tools provide real-time reputation tracking, spam placement visibility, and early warnings before issues escalate. They offer clarity where outreach platforms fall short.
MailReach helps you stay ahead of inbox issues, recover from dips in sender reputation, and make sure your emails reach people who matter.
Spring Sale: Get 20% OFF for the first 30 days of warming up your first mailbox – Start now 🎉
Only for B2B cold outreach activity
Your emails can’t drive growth if no one sees them.
Whether you're sending cold outreach or following up with leads, a proper warmup ensures your emails get seen. Make sure your best campaigns don’t go to waste.
Your B2B cold emails deserve great deliverability.
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.
Email Deliverability
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