You can write the perfect email… but what’s the point if it never reaches the inbox?

Email deliverability is often the hidden villain behind low response rates, stalled pipelines, and poor conversion, even if your cold outreach game is strong.

If your emails are consistently landing in spam folders, getting throttled by ESPs (Email Service Providers), or triggering blacklists, you’ve got a problem bigger than your subject line.

Luckily, that’s where email deliverability tools come in.

These tools help you monitor, test, and optimize your entire sending framework—from domain health and spam triggers to inbox placement and IP reputation.

In this post, we’ll break down the top tools that help ensure your emails don’t end up in spam, starting with one of the most powerful solutions on the market today:

How We Evaluated These Tools to List Them?

To provide you with the best email deliverability tools, here’s how I evaluated them:

I used each tool, ran trial campaigns, and compared real results. I reviewed 15 to 20 tools and picked only those that actually improve deliverability.

Why should you trust this list? Because I’ve tested these tools myself.

Core evaluation factors:

• Accuracy and reliability: Real-time, consistent data.
  
• Features: Spam testing, warm-up, DNS diagnostics, inbox placement.
  
• Pricing: Good value, transparent tiers.
  
• User reviews: Validated by G2, Capterra, and real users.

Top 9 Email Deliverability Tools that Ensures Emails Don't End up in Spam

1. Smartlead – Premium Deliverability at Scale

Smartlead is built to maximize inbox placement for cold emailers, sales teams, and lead gen pros. Whether you’re running multi-domain outreach or high-volume campaigns, it offers the automation muscle and tech safeguards you need to land in the inbox, not the spam folder.

Why Smartlead Stands Out

• Auto-Rotating Email Accounts: No more getting flagged for sending too much from one mailbox. Scale safely with automatic rotation across domains and inboxes.
  
• AI-Powered Warmups: Warm up your email accounts using Smartlead’s network of 1.6M+ mailboxes (Outlook, Gmail, etc.)—with human-like sending and engagement behavior.
  
• ESP Matching: Dynamically match your sending ESP to your recipient’s inbox provider. This feature alone can boost deliverability by 16%.
  
• Real-Time AI Optimization: Smartlead's AI adjusts sending patterns in real time to protect your sender reputation and react to low engagement signals.
  
• IP Infrastructure: You get unique, pre-warmed IPs per campaign. No more worrying about shared IPs or getting punished for someone else’s mistakes.
  
•  Natural Email Simulation: Plain text emails, randomized patterns, and spintax make your emails look and feel like human messages.
  

“Smartlead helped us achieve a 2.48% conversion rate and expand our client base. I’d rate it 10/10 for satisfaction.”
– Romain Osman, Co-Founder, Five Element

 ✅ Best-in-class deliverability
✅ Insanely scalable
✅ Smart AI + auto everything
✅ 14-day free trial

Other Tools to Support Email Deliverability

While Smartlead offers an all-in-one solution, here are a few specialized tools that can support or complement your email infrastructure:

2. TrulyInbox – Inbox Placement & Deliverability Testing

TrulyInbox focuses on building your sender reputation so emails land in the primary inbox, not spam.

How it Helps:

• Reduces spam complaints through engagement automation.
  
• Gradually increases volume to avoid deliverability drops.
  
• Stops sending if SPF/DKIM/DMARC aren’t configured.
  

Key Features:

• Custom warm-up volume control
  
• Advanced engagement simulation (opens, stars, replies)
  
• Auto-stop on setup issues
  
• Real-time inbox placement dashboard
  
• Deliverability scoring
  

 3. GlockApps – Inbox Testing & Spam Filter Analysis

GlockApps helps you test where your emails land across Gmail, Outlook, Yahoo, etc., and gives suggestions to avoid spam filters.

Features:

• Inbox placement across 70+ seed accounts
  
• Spam trigger analysis (SpamAssassin, Barracuda)
  
• DNS and authentication audits
  
• Blacklist monitoring
  

4. MxToolbox – Infrastructure Diagnostics

MxToolbox is your go-to for DNS lookups, authentication record validation, and blacklist monitoring.

Great For:

• SPF/DKIM/DMARC troubleshooting
  
• SMTP & MX server analysis
  
• DNS record consistency
  
• Blacklist alerts
  

5. Folderly – Warm-Up and Spam Prevention Tool

Folderly is known for its spam testing, deliverability dashboards, and AI-powered warm-up features.

Features:

• Spam placement detection
  
• Real-time spam alerts
  
• Email interaction simulation
  
• Domain health reporting
  

6. Everest by Validity – Full Suite for Deliverability & Analytics

Everest combines tools from Return Path, BriteVerify, and 250ok to give you an enterprise-level email performance suite.

Features:

• Inbox placement testing with 100+ ESPs
  
• Reputation monitoring (Sender Score, traps)
  
• List validation
  
• Competitor analysis
  

 7. Google Postmaster Tools – Free Gmail Performance Insights

If you send bulk emails to Gmail, this free tool is a must.

Features:

• Domain reputation reporting
  
• Authentication verification
  
• Spam complaint tracking
  
• Delivery error insights
  

 8. Postmark – Fast Transactional Email Delivery

Postmark ensures transactional emails (resets, receipts, alerts) get delivered in seconds with detailed tracking.

Why Use It:

• Blazing fast delivery
  
• Bounce and spam complaint tracking
  
• Separate transactional from marketing mail
  

9. InboxAlly – Reputation Repair & Warm-Up Automation

InboxAlly helps train email providers to trust your domain through highly targeted engagement strategies.

Key Features:

• Custom warm-up plans
  
• Inbox vs spam placement analytics
  
• Reputation repair modes
  
• Live deliverability dashboard
  

Best Practices to Stop Landing in Spam and Improve Email Deliverability

If your emails are landing in spam folders, it can seriously hurt your B2B outreach efforts.

The good news?

With the right strategies, you can improve your email deliverability and make sure your messages reach the inbox.

Here’s how to boost your email deliverability and keep your outreach out of spam:

1. Set Up SPF, DKIM, and DMARC for Your Domain

Email authentication protocols like SPF, DKIM, and DMARC are essential for building trust with email providers and improving deliverability.

• SPF (Sender Policy Framework): This tells email servers which IP addresses are allowed to send emails on behalf of your domain. To set it up, add an SPF TXT record in your domain’s DNS settings.
  
  
• DKIM (DomainKeys Identified Mail): DKIM adds a unique digital signature to your emails, proving they’re really from you. You’ll need to generate DKIM keys and publish the public key as a DNS TXT record.
  
  
• DMARC (Domain-based Message Authentication, Reporting & Conformance): DMARC links SPF and DKIM together and tells email servers what to do if authentication fails (e.g., reject or quarantine suspicious emails). Add a DMARC TXT record in your DNS to configure this.
  
  

Setting up these three protocols properly signals to inbox providers that your emails are trustworthy — which helps keep your messages out of spam.

2. Warm Up Your IP Address Gradually

When sending emails from a new IP address, it’s important to “warm it up” slowly. This means gradually increasing the volume of emails you send over time, so email providers recognize you as a legitimate sender.

Tools like Smartlead automate this process, safely ramping up your sending volume and protecting your sender reputation. Smartlead even moves emails caught in spam back to the inbox, marking them as important — a smart way to build trust with email providers.

To get started with Smartlead warm-up:

• Log in to the Smartlead app.

• Go to the “Email Accounts” tab.
  
• Select your email and follow the prompts to set up automated warm-up.
  

Smartlead supports Gmail, Outlook, Zoho, and more — making it easy to maintain a strong sending reputation.

3. Avoid Spam Trigger Words and Tactics

Certain words and formatting can trigger spam filters — and tank your deliverability. Avoid using terms like “free,” “discount,” or “act now.” Also, stay away from:

• Writing in ALL CAPS
  
• Excessive punctuation (!!! or ???)
  
• Overly salesy or hype-heavy language
  

Instead, focus on clear, helpful, and relevant content that adds real value to your recipients.

4. Clean and Segment Your Email Lists Regularly

Keeping your email list clean is key to good deliverability. Remove email addresses that bounce or are inactive to maintain a healthy list.

Segmentation is equally important. Group your contacts based on their interests, behaviors, or demographics.

Sending more targeted emails improves engagement — which tells inbox providers you’re sending valuable content and boosts your inbox placement.

FAQs About Email Deliverability Tools

Q1. What’s the difference between delivery and deliverability?

Delivery means your email successfully reached the recipient’s mail server. This means the message was accepted by the server, but it doesn’t guarantee the user ever saw it.

Deliverability refers to your email actually landing in the recipient’s inbox, not the spam folder, promotions tab, or any other folder. Good deliverability means your email avoids spam filters and gets noticed by your recipients.

Q2. What causes emails to land in spam?

There are several common reasons why emails end up in spam folders:

1. Poor sender reputation: If your sending domain or IP has a history of spam complaints or sending to invalid addresses, ISPs (like Gmail, Outlook) will flag your emails.
   
2. Missing or incorrect SPF, DKIM, and DMARC records: These authentication protocols verify that you are authorized to send emails from your domain. Without them, your emails look suspicious.
   
3. Spammy content: Use of certain keywords, excessive links, all caps, or misleading subject lines can trigger spam filters
   
4. Bad list hygiene: Sending emails to outdated or purchased lists with many invalid addresses or spam traps can damage your reputation quickly.
   
5. Lack of engagement: ISPs track how users interact with your emails (opens, clicks, replies). Low engagement can signal your emails are unwanted.
   

Q3. Do I need multiple deliverability tools?

It depends on your use case and budget. Here’s a simple breakdown:

• Cold email outreach: Use Smartlead for warm-ups, rotation, and inbox optimization at scale.
  
  
• Warm-up & spam testing: Tools like TrulyInbox and InboxAlly help you build reputation gradually and avoid spam.
  
  
• Technical diagnostics: Use MxToolbox to verify DNS records, check for blacklisting, and ensure proper email authentication.
  
  
• All-in-one enterprise solutions: If you want everything—monitoring, analytics, testing, reputation management—consider Everest by Validity, though it’s pricier.
  

Often, a combination of tools covering warm-up, diagnostics, and analytics offers the best results.

Q4. How do I check SPF, DKIM, and DMARC records?

• Use MxToolbox’s SPF, DKIM, and DMARC lookup tools to verify if these records are published correctly on your domain’s DNS.
  
• GlockApps can test these as part of a full spam filter and inbox placement report.
  
• Google Postmaster Tools also reports on authentication issues if you send bulk emails to Gmail addresses.
  

Make sure these records are properly configured and aligned to prevent spoofing and improve your sender reputation.

Q5. How do I check if my domain or IP is blacklisted?

Being blacklisted means your domain or sending IP is flagged as a spam source, which drastically lowers deliverability.

• Use MxToolbox’s, Smartdelivery blacklist checker to scan major blacklists like Spamhaus, Barracuda, SORBS, and others.
  
• GlockApps also monitors blacklists as part of its spam testing.
  

If you find your IP or domain on a blacklist, investigate the cause (usually spam complaints or sending to bad lists), then follow the blacklist’s removal process.

Regular blacklist monitoring is crucial to prevent sudden drops in inbox placement.

Q6. How important is email warm-up, and how do deliverability tools help with it?

Email warm-up is the gradual process of increasing your sending volume and engagement to build a positive reputation with ISPs.

• Sending a large volume of emails from a new domain or IP too quickly often triggers spam filters.
  
• Deliverability tools like Smartlead, TrulyInbox, and InboxAlly automate warm-up by simulating opens, clicks, and replies, and by controlling send volume.
  
• Warm-up tools help establish trust with mailbox providers, improving your long-term inbox placement.
  

Q7. Can these tools help with content optimization to avoid spam filters?

Yes, many deliverability tools offer spam scoring and content analysis features.

• For example, GlockApps scans your email for spam triggers like excessive links, suspicious phrases, or bad formatting.
  
• Some tools provide suggestions to improve subject lines and body content to reduce spam filter flags.
  
• Content optimization combined with technical compliance ensures maximum inbox delivery.
  

Q8. What metrics should I track to measure email deliverability success?

Track these key metrics:

• Inbox placement rate: Percentage of emails that land in the inbox vs spam or promotions.‍
• Bounce rate: Emails that fail to deliver.‍
• Spam complaint rate: Number of recipients marking your emails as spam.‍
• Engagement rate: Clicks, replies, and other interactions.
  

Most deliverability tools provide dashboards with these metrics to help you optimize campaigns continuously.

Deliverability is the Hidden Lever for Growth

If your emails don’t reach your audience, nothing else matters.

Deliverability isn’t just about avoiding spam filters—it’s about building a system where your outreach always lands in the right place, at the right time. 

With Smartlead, you get everything you need to scale safely, automate intelligently, and convert cold prospects into warm leads, without ever worrying about spam.