Best Email Deliverability Tools for Sales Teams [2026]
Your SDR team just sent 500 cold emails. Open rate? 4%. Not because the copy was bad — because 80% of those emails never reached the inbox.
Email deliverability is the silent killer of outbound sales. You can have perfect ICP targeting, a compelling value prop, and flawless follow-up sequences. None of it matters if your emails land in spam.
The average B2B email deliverability rate hovers around 83%, according to EmailToolTester's 2025 testing data. That means nearly 1 in 5 emails never reaches the intended recipient. For outbound cold email — where sender reputation starts lower — the numbers are even worse.
This guide breaks down 14 email deliverability tools across every category a sales team needs: warmup, authentication monitoring, inbox placement testing, email validation, and all-in-one platforms that bundle deliverability into their outbound stack.
Why Email Deliverability Matters More in 2026
Three things changed in the last 12 months that make deliverability harder than ever:
1. Google and Yahoo's sender requirements (enforced since Feb 2024) Both providers now require SPF, DKIM, and DMARC authentication for bulk senders. One-click unsubscribe headers are mandatory. Spam complaint rates above 0.3% trigger throttling. These aren't suggestions — violations mean your emails get blocked.
2. AI-powered spam filters are smarter Gmail's latest spam filtering uses RETVec (Resilient & Efficient Text Vectorizer) to detect spam patterns that bypass traditional keyword filters. Microsoft's SmartScreen filters analyze sender behavior patterns across their entire network. Generic templates get caught faster than ever.
3. Cold email volume is exploding Tools like Instantly, Lemlist, and SmartLead made it trivially easy to send thousands of cold emails daily. The result? ISPs are more aggressive about filtering unfamiliar senders. Standing out requires pristine technical setup AND genuine engagement signals.
Categories of Email Deliverability Tools
Before diving into specific tools, understand the five categories:
| Category | What It Does | When You Need It |
|---|---|---|
| Email Warmup | Gradually builds sender reputation by simulating real email conversations | New domains, new mailboxes, or recovering from spam flags |
| Inbox Placement Testing | Shows where your emails land (inbox, spam, promotions) across providers | Before launching campaigns, ongoing monitoring |
| Authentication Monitoring | Verifies SPF, DKIM, DMARC records and alerts on issues | Always — misconfigurations happen silently |
| Email Validation | Removes invalid, disposable, and risky email addresses from lists | Before every outbound campaign |
| All-in-One Platforms | Bundle warmup + sending + deliverability monitoring into one tool | Teams that want simplicity over best-of-breed |
The 14 Best Email Deliverability Tools
1. MarketBetter — Signal-Driven Outbound with Built-In Deliverability
Best for: B2B sales teams that want deliverability baked into their outbound workflow, not bolted on.
Most deliverability tools fix a symptom — your emails hitting spam. MarketBetter fixes the root cause: sending the wrong emails to the wrong people at the wrong time.
MarketBetter's email automation layer includes built-in deliverability infrastructure — domain warmup, send throttling, rotation across multiple mailboxes, and bounce monitoring. But the real deliverability advantage is upstream: the Daily SDR Playbook prioritizes prospects showing active buying signals (website visits, content engagement, champion job changes), so your emails go to people who actually want to hear from you.
Higher engagement rates → better sender reputation → better deliverability. It's a virtuous cycle that no standalone warmup tool can replicate.
Key deliverability features:
- Automated mailbox warmup and rotation
- Smart send throttling based on domain reputation
- Bounce and complaint rate monitoring
- Signal-based targeting that improves engagement metrics naturally
- Hyper-personalized sequences that avoid template spam triggers
Pricing: Starting at $500/mo (Starter), $1,500/mo (Growth), $3,000/mo (Scale)
Best for teams who: Want to solve deliverability at the strategy level, not just the technical level.
2. Warmup Inbox — Pure Email Warmup Specialist
Best for: Teams that need to warm up new domains or recover damaged sender reputation.
Warmup Inbox connects to your email account and automatically sends and receives emails with a network of real inboxes. These simulated conversations build your sender reputation gradually, teaching ISPs that your domain sends legitimate email.
What stands out:
- Network of 20,000+ real inboxes for warmup exchanges
- Inbox placement monitoring included (not just warmup)
- SPF, DKIM, DMARC authentication checker
- Spam score analysis for individual emails
- Detailed reporting on reputation progress over time
Pricing: Starting at $15/mo per inbox. Volume discounts available for teams.
Limitations: Warmup only — no sending, no sequences, no prospect discovery. You'll need a separate outbound tool.
3. GlockApps — The Deliverability Testing Standard
Best for: Sales ops teams that need detailed inbox placement data across every major email provider.
GlockApps is what EmailToolTester uses for their own deliverability benchmarks — that's a strong endorsement. It tests where your emails land (inbox, spam, promotions, missing) across Gmail, Outlook, Yahoo, and dozens of other providers using seed lists.
What stands out:
- Inbox placement testing across 30+ email providers
- DMARC analytics and monitoring dashboard
- IP and domain reputation monitoring
- Spam filter testing (SpamAssassin, Barracuda, etc.)
- Uptime monitoring for mail servers
Pricing: Free plan (2 tests/day). Paid plans from $79/mo (Business) to $149/mo (Enterprise).
Limitations: Testing and monitoring only. No warmup, no sending, no validation. Best used alongside an outbound platform.
4. Instantly — All-in-One Cold Email with Strong Warmup
Best for: High-volume outbound teams that want sending + warmup in one platform.
Instantly made its name with unlimited email warmup included in every plan. Their warmup network exchanges emails between Instantly users, building reputation automatically. Combined with their sending infrastructure (unlimited email accounts, smart rotation), it's a popular choice for outbound-heavy teams.
What stands out:
- Unlimited email warmup included in all plans
- Smart mailbox rotation across unlimited accounts
- Built-in email validation
- Campaign analytics with deliverability metrics
- Lead database (paid add-on) for prospect sourcing
Pricing: $30/mo (Growth — 5,000 emails), $77.60/mo (Hypergrowth — 25,000 emails), $286.30/mo (Light Speed — 500,000 emails).
Limitations: Warmup network is other Instantly users — engagement is simulated, not real buyer signals. Volume-first approach can damage reputation if targeting isn't precise. No visitor identification or intent signals.
5. Lemlist — Personalization-First Deliverability
Best for: Teams where email personalization is the primary deliverability strategy.
Lemlist's thesis: hyper-personalized emails get higher engagement, which improves deliverability naturally. Their platform includes email warmup (via Lemwarm), but the real value is in personalization features — custom images, dynamic landing pages, and liquid syntax variables that make every email feel 1:1.
What stands out:
- Lemwarm automated warmup with 10M+ warmup emails/month across network
- Custom image and video personalization
- Email verification built into the workflow
- Multi-channel sequences (email + LinkedIn + calls)
- Deliverability dashboard with inbox placement estimates
Pricing: $39/mo (Email Starter), $69/mo (Email Pro), $99/mo (Multichannel Expert), $159/mo (Outreach Scale).
Limitations: Warmup is basic compared to dedicated tools. Personalization requires manual effort to set up effectively. Gets expensive at scale with multiple seats.
6. ZeroBounce — Enterprise-Grade Email Validation
Best for: Teams with large prospect lists that need thorough validation before campaigns.
ZeroBounce validates email addresses against 200+ data points to catch invalid, disposable, abuse, and spam-trap addresses before they damage your sender reputation. A single hard bounce can hurt your domain for weeks — ZeroBounce prevents that.
What stands out:
- 200+ validation checks per email address
- Catches spam traps, abuse emails, and catch-all domains
- Email scoring (likelihood of engagement)
- Inbox placement testing included
- Blacklist monitoring for your sending domains
- API for real-time validation in forms and workflows
Pricing: Pay-as-you-go from $0.008/email. Monthly plans from $40/mo (2,000 validations) to $975/mo (100,000 validations).
Limitations: Validation only — you still need a separate sending platform and warmup tool.
7. Mailtrap — Developer-Friendly Testing + Monitoring
Best for: Teams with in-house developers who want to test email rendering and deliverability before going live.
Mailtrap started as an email testing sandbox for developers and evolved into a full deliverability monitoring platform. Unique value: test your emails in a safe environment before sending to real recipients.
What stands out:
- Email sandbox for testing without sending to real inboxes
- Inbox placement testing across major providers
- HTML email analysis and spam scoring
- Sending infrastructure (Email API) with built-in deliverability monitoring
- Detailed logs showing why specific emails were filtered
Pricing: Free plan (100 test emails/mo). Business plans from $10/mo to $85/mo.
Limitations: More developer-oriented than sales-oriented. The testing sandbox is powerful but may be overkill for SDR teams that just need warmup and monitoring.
8. SmartLead — Volume-Optimized Deliverability
Best for: Teams sending 10,000+ cold emails per month who need robust infrastructure.
SmartLead's infrastructure is built for volume. Unlimited mailboxes, unlimited warmup, auto-rotation, and a massive warmup network. Their Master Inbox aggregates replies from all mailboxes into one view, so your team isn't juggling 20 inboxes.
What stands out:
- Unlimited email accounts and warmup (all plans)
- Auto-rotation across mailboxes to distribute send volume
- Subsequence automation based on prospect behavior
- Master Inbox for unified reply management
- Built-in email verification
- White-label for agencies
Pricing: $39/mo (Basic — 6,000 emails), $94/mo (Pro — 150,000 emails), $174/mo (Custom — 12M emails).
Limitations: Volume-first philosophy can create deliverability problems if targeting is poor. No intent signals or visitor identification. Agency-focused features add complexity for in-house teams.
9. Folderly — AI-Powered Deliverability Recovery
Best for: Teams with damaged sender reputation that need to recover fast.
Folderly uses AI to diagnose why your emails hit spam and prescribes specific fixes. Their email warm-up simulates real conversations, and their content analysis identifies spam triggers in your copy. Particularly useful for teams that have already damaged their reputation and need structured recovery.
What stands out:
- AI-driven spam trigger identification in email content
- Automated warmup with engagement simulation
- DNS and authentication auditing
- Deliverability scoring and trend tracking
- Domain health monitoring
Pricing: Starting at $120/mo per mailbox (includes warmup + monitoring + content analysis).
Limitations: Expensive compared to dedicated warmup tools. Best value when you're recovering from deliverability problems, not preventing them.
10. Validity Everest (formerly Return Path) — Enterprise Deliverability Intelligence
Best for: Enterprise teams with complex sending infrastructure who need deep analytics.
Validity Everest is the enterprise standard for inbox placement monitoring. Their seed list network is the largest in the industry, and their analytics go deep — deliverability by ISP, by campaign, by sending IP, over time. If your org sends millions of emails, this is the monitoring layer.
What stands out:
- Largest seed list network for inbox placement testing
- Deliverability analytics by ISP, campaign, IP, and domain
- Competitive benchmarking (how your deliverability compares to industry)
- Sender certification program (whitelist with major ISPs)
- Integration with major ESPs and marketing automation platforms
Pricing: Custom pricing (enterprise). Typically $500-2,000+/mo depending on volume and features.
Limitations: Enterprise pricing and complexity. Overkill for teams sending under 50,000 emails/month. Monitoring only — no warmup or sending.
11. Warmy — Automated Warmup with AI Optimization
Best for: Teams that want set-and-forget warmup with AI-driven pacing.
Warmy's AI analyzes your email account's current reputation and automatically adjusts warmup volume and pacing. Higher-reputation accounts ramp faster; damaged accounts get slower, more careful warmup. Real engagement simulation (opens, replies, removes from spam) across their network.
What stands out:
- AI-driven warmup pacing based on current reputation
- Real engagement simulation (opens, replies, spam removal)
- Email template checker for spam triggers
- Deliverability testing across providers
- Domain health monitoring
Pricing: $49/mo (Starter), $129/mo (Business), $189/mo (Premium) per mailbox.
Limitations: Warmup-focused with some monitoring. No sending infrastructure, no prospect discovery, no sequences.
12. Mailgun Optimize — API-First Deliverability
Best for: Technical teams that need deliverability tools accessible via API.
Mailgun Optimize (formerly InboxReady) provides inbox placement testing, email validation, and deliverability analytics through a developer-friendly API. If your team builds custom outbound tools or has proprietary sending infrastructure, Mailgun Optimize integrates cleanly.
What stands out:
- Inbox placement testing via API
- Email validation (real-time and bulk)
- Deliverability analytics and reporting
- Blocklist monitoring
- Integration with Mailgun's sending infrastructure
Pricing: Included with Mailgun plans (from $35/mo for 50,000 emails). Standalone Optimize pricing available on request.
Limitations: Requires technical implementation. Not a standalone tool for non-technical sales teams.
13. MxToolbox — Free DNS and Authentication Monitoring
Best for: Any team that needs to verify their email authentication setup is correct.
MxToolbox is the go-to free tool for checking DNS records, SPF/DKIM/DMARC configuration, and blacklist status. Every sales ops team should have this bookmarked — it's the fastest way to diagnose authentication problems that tank deliverability.
What stands out:
- Free SPF, DKIM, DMARC record checker
- Blacklist monitoring across 100+ blacklists
- MX record lookup and mail server diagnostics
- SMTP testing
- Domain health reports
Pricing: Free for basic lookups. Pro plans from $129/mo for continuous monitoring and alerts.
Limitations: Diagnostics only. Shows you what's wrong but doesn't fix it. No warmup, no validation, no sending.
14. Unspam.email — Visual Spam Testing
Best for: Teams that want a quick visual preview of how their emails render and where they land.
Unspam.email provides a visual heatmap of your email (showing where recipients' eyes will focus) combined with inbox placement testing and spam score analysis. Unique visual approach to deliverability testing.
What stands out:
- Email heatmap showing predicted eye-tracking patterns
- Inbox placement testing across major providers
- Spam score analysis
- Authentication check (SPF, DKIM, DMARC)
- Design accessibility testing
Pricing: Free plan (5 tests/mo). Paid plans from $9/mo.
Limitations: Testing only. Useful as a pre-send check but doesn't replace warmup or monitoring.
How to Build Your Email Deliverability Stack
Most sales teams need tools from at least three categories. Here's what a solid stack looks like at different stages:
Early Stage (Under 1,000 emails/month)
- Warmup: Use your outbound platform's built-in warmup (Instantly, Lemlist, or MarketBetter)
- Validation: ZeroBounce or NeverBounce for list cleaning
- Monitoring: MxToolbox (free) for authentication checks
- Monthly cost: $50-100
Growth Stage (1,000-10,000 emails/month)
- All-in-one: MarketBetter (signal-driven outbound + built-in deliverability) or Instantly (volume-focused)
- Validation: ZeroBounce for list hygiene
- Testing: GlockApps for inbox placement monitoring
- Monthly cost: $200-500
Scale Stage (10,000+ emails/month)
- Platform: MarketBetter for signal-based outbound with deliverability infrastructure
- Monitoring: GlockApps or Validity Everest for detailed placement analytics
- Validation: ZeroBounce (API integration for real-time validation)
- Recovery: Folderly if reputation damage occurs
- Monthly cost: $500-2,000+
The Deliverability Metric That Actually Matters
Most teams obsess over inbox placement rate. That's the wrong metric.
The metric that matters is reply rate. Here's why:
ISPs like Gmail and Microsoft track engagement signals — opens, clicks, replies, and forwards. High engagement tells the ISP your emails are wanted. Low engagement (or worse, spam complaints) tells them your emails are unwanted.
A tool that warms up your inbox and gets you to 95% inbox placement doesn't help if your emails get ignored once they arrive. You need:
- Right targeting — Send to prospects with buying intent, not cold lists
- Right timing — Reach out when signals indicate interest
- Right message — Personalize based on actual prospect behavior
- Right infrastructure — Clean authentication, proper warmup, validated lists
This is why signal-driven platforms like MarketBetter approach deliverability differently. Instead of optimizing the last mile (inbox placement), they optimize the first mile (who you email and why). The deliverability improvement is a natural consequence.
Bottom Line
Email deliverability isn't a problem you solve once — it's an ongoing discipline. Authentication settings drift. Domains get blacklisted. ISP rules change. New mailboxes need warmup.
The best approach combines:
- Technical infrastructure (authentication, warmup, validation)
- Strategic targeting (intent signals, buyer behavior, timing)
- Ongoing monitoring (inbox placement, reputation, complaint rates)
Standalone warmup tools fix symptoms. All-in-one platforms with built-in deliverability (like MarketBetter) fix the root cause by ensuring your emails go to people who actually want to hear from you.
Ready to fix your email deliverability at the source? Book a demo with MarketBetter →