Do you rely on email to communicate with customers? Just about every business does. We often don‘t realize how much revenue depends on our email campaigns actually reaching inboxes. Studies show that upwards of 30% never make it to the recipient due to security blocks, spam filters, or other impediments.
Losing one third of your emails is no joke – most companies would go out of business if offline channels like phone or mail were that unreliable!
The root of email deliverability starts with the SMTP server responsible for routing messages. Just a single misconfiguration can cause mass failures. That‘s why regularly testing your SMTP infrastructure with the tools in this guide provides hard value.
Why Should You Care About Your SMTP Server?
We all use email without giving the underlying delivery process a second thought. SMTP servers speak a language called Simple Mail Transfer Protocol (SMTP) to send your messages through various checkpoints before landing at the destination inbox.
The process works when all the players – your IP, domain, mail host, ISP, and recipient server – cooperate smoothly. Hiccups in any part of the chain can have catastrophic consequences for both one-to-one messages and mass email campaigns.
Studies indicate that optimized email deliverability provides shocking business gains:
- Over 30% higher open rates
- 25% increase in click-through-rates
- Revenue boost as high as 41% YoY
Conversely, not properly testing and safeguarding your SMTP infrastructure leads to:
- Up to 25% of all emails blocked entirely
- Over 50% of messages sent to spam folders
- Increased bounced messages and complaints
Despite the clear impact, only 23% of companies have visibility into the underlying health of their SMTP servers and configurations according to Gartner.
The key protocols that enable routing differ in purpose:
- SMTP transports mail BETWEEN servers
- IMAP/POP3 RETRIEVES messages to your inbox
- MSA ACCEPTS mail from sender‘s client
Within SMTP, authentication means your identifying credentials are valid to send mail through servers.
This guide will explore 17 tools to optimize the foundation of emailing: your SMTP delivery.
Benefits of Leveraging SMTP Testing Tools
Taking control of SMTP performance provides real business wins:
- Save on costs: Poor deliverability wastes money resending blocked messages and dampens campaign ROI.
- Security: Vulnerabilities like open relays put privacy at risk.
- Fix issues preemptively: Before customers complain about missing emails.
- Increase revenue: Higher open rates directly translate to sales.
Research pegged savings from proactive testing at over $150,000 for mid-market companies.
Here are specific gains the right SMTP tools deliver:
- Identify security risks before disruption
- Reduce bounce rates landing emails in spam
- Detect configuration causes of failure
- Check encryption methods and certificates
- Confirm authentication works properly
- Validate reputation of domains, IPs
Top providers like SendGrid estimate up to 15% revenue growth simply by optimizing email delivery through proper SMTP monitoring and testing.
Let‘s explore the 17 best SMTP testing tools available now.
1. SocketLabs Diagnostics
SocketLabs provides full-featured diagnostics 100% free. You get checks for:
- Basic SMTP connections/credentials
- Secure (SSL) and open servers
- Lightweight downloadable size
- Built-in SMTP test command library
- Windows and .NET framework compatible
The tool is extremely lightweight while still packed with pro-grade capabilities.
2. MxToolbox Blackbox
MxToolbox focuses on rapid connection, relay, and DNS diagnostics:
- Quick validation of reverse DNS/PTR
- Calculate response times
- Instant MX record lookups
- Clear pass/fail testing
Rather than advanced configurations, MxToolbox delivers completely free baseline validations.
3. Wormly
Wormly provides email address verification and handshake testing.
I like how flexible the interface is:
- Use SMTP IP or domain
- Verify test email addresses
- Override default SMTP port number
- View detailed session logs
Wormly makes it easy to simulate sending from your actual accounts.
4. CheckTLS
CheckTLS runs a security audit of encryption protocols and email compliance.
Staying legal and safe means ensuring:
- Email privacy, legal compliance
- Adherence to regulations like HIPAA
- Fixing detected encryption issues
I wish more tools focused on the compliance aspect instead of just deliverability.
5. SSL-Tools
SSL-Tools evaluates your SMTP encryption strength specifically:
- Checks for STARTTLS usage & cert validity
- Provides Perfect Forward Secrecy support details
- Tests Heartbleed vulnerabilities
It‘s useful even if you use a 3rd party email provider since the underlying connections still rely on SMTP.
6. ImmuniWeb
ImmuniWeb provides versatile free security testing:
- Email servers
- Web servers
- SSL certificates
- Compliance benchmarks like PCI
One of the only free tools providing commercial-grade infrastructure scanning.
7. DNSQueries
DNSQueries offers simple SMTP server health monitoring:
- Basic connectivity testing
- Send test emails
- Direct stdout logging
It‘s perfect for quickly confirming your DNS and mail server respond correctly.
8. SMTPTester
SMTPTester is a Python script detecting three common vulnerabilities:
- Email spoofing risks
- User enumeration through VRFY
- Open relays
It‘s ideal for manual penetration testing and determining if your current SMTP provider has locked down security properly.
9. Header Analyzer
This toolkit parses raw email headers for tracking and forensics:
- Paste full headers
- Instant analysis
Getting to the bottom of intermittent sending issues can be simplified by looking at the message flow hidden in headers.
10. Microsoft Remote Connectivity Analyzer
Part of the Exchange Toolkit, Microsoft‘s offering diagnoses environment-specific factors:
- Tests inbound and outbound delivery
- Provides sender reputation details
- Checks reverse DNS/RBL blocklists
If you utilize Exchange or Office 365, this tool should be part of your optimization toolkit.
11. NetScanTools Pro
NetScanTools Pro delivers robust mail flow testing through:
- Configurable test message generator
- SMTP relay testing
- 15+ validation checks
- Granular logging at protocol level
Deep SMTP message generation and parsing capabilities for advanced users.
Other Key Solutions
The previous 11 tools represent fully-featured capabilities usable by nearly any industry. The remaining 6 specialize in specific capabilities:
SMTPPing: Latency, throughput, and variation calculations
Mailpit: Fast SMTP test server with web interface
MailHog: Local test mail server
LunaticSMTP: Extensible fake Java SMTP server
MailDev: Smooth SMTP test server UI
Mailocal: Quick PHP-based local SMTP
Key Selection Criteria
Choosing your best SMTP test tool depends on your use case, infrastructure, and teams. I would evaluate primarily on:
- Supported integrations
- Convenience/usability
- Advanced features needed
- Pricing
Fortunately, many of the tools above have free versions for getting started.
To select the best commercial or enterprise-scale tool, compare across:
| Tool | Email Services Integration | Support Options |
|---|---|---|
| SocketLabs | MS Exchange, G Suite | Email, chat, phone, remote assistance |
| Mxtoolbox | Office 365, Gmail | Email, knowledgebase |
| CheckTLS | Outlook, Yahoo, iCloud | Phone, ticket system |
And so on for each option. Many providers offer test periods or freemium versions to validate capabilities before paying.
Getting Started With SMTP Testing
While tools vary in scope and depth, best practices apply universally:
Establish a baseline – Perform initial testing across core parameters
Set a recurring schedule – Monthly or quarterly testing as a "checkup"
Test before launch – Validate new ESP integrations before activatiob
Follow up on failures – Diagnose and resolve to prevent future issues
Share metrics proactively – Make team aware of DNS/IP/auth changes
Start by checking connections, encryption, routes, and security first. Then explore advanced tools drilling into configurations.
Work with your IT/InfoSec teams to review results and optimize over time.
Real-World Examples and Use Cases
The right SMTP tool choice depends greatly on your specific infrastructure and business needs.
For small business, free or freemium tools like SocketLabs, MXToolbox, or MailHog work well for basic tests. Checking deliverability periodically prevents the huge pain of finding years of emails in spam.
Mid-market companies gain extensive value from commercial-grade solutions like Wormly, CheckTLS, and NetScanTools Pro. You need automation, integrations, and customer support as dedicated email becomes crucial for growth.
Specific vertical use cases include:
- SMTP ping tools for ISPs and ESPs monitoring infrastructure
- Compliance policy testing for healthcare, finance, education, government
- Self-service testing for IT consultants and technical teams
Deliverability starts degrading rapidly after the first failure without swift diagnosis.
Enterprise organizations require extensive capabilities from providers like SocketLabs, 250ok, and Mailgun. Benefits magnify with volume through:
- Personalization across segments and personas
- Integrations bridging CRM, marketing automation, etc.
- Scalability to maintain speed with expanding audiences
- Alerting when metrics fall below success thresholds
Testing enables behavior-based triggers driving failover capability and instant visibility if deliverability drops.
Why Now for SMTP Testing?
With growing reliance on email, requirements have increased for deliverability and compliance:
- Increasing volumes make failures more prevalent
- New privacy regulations impose legal requirements
- Growing zero trust security means controlling your own stack
- More rejection factors as filters become advanced
Simultaneously, threats from phishing, business email compromise, and spam have grown exponentially in recent years:
- 280% higher spoofing attacks
- Financial losses topping $43 billion by 2023
Taken together, the case for direct ownership of email infrastructure health is stronger than ever.
The Future of SMTP Testing
In coming years, capabilities leveraging AI, expanded datasets, and ubiquity of APIs will improve testing further:
- Predictive analytics to model deliverability factors
- Greater automation for continuous optimization
- Customer journey mapping showing exact fail points
As sensors and data collection grows exponentially across tech, so too will precision around email flows.
Instead of annual or quarterly testing, operations teams can diagnose and resolve delivery problems immediately using centralized platforms. Integrating SMTP management into existing dashboards and workflows prevents delivery surprises.
The tools in this guide represent an excellent starting point to strengthen the backbone of engagement.
Key Takeaways
If your business depends on communicating via email, keep these core recommendations in mind:
- Prioritize testing and monitoring of your underlying SMTP infrastructure
- Set specific schedules and response processes to resolve inevitable issues
- Choose tools aligning integration support, specific personnel expertise, and use case
- Compare capabilities and support plans to identify the best long-term partner(s)
- Incorporate email pathway transparency into operations metrics and dashboarding
Deliverability drives revenue growth while preventing disruption and non-compliance scenarios before they damage credibility.
With expanding threat surfaces from phishing and spoofing, direct control over sender authentication and security saves money. So does reducing repeated sending or missing key customer messages.
Now you have a better understanding of 17 capable tools ready to optimize your foundation for outreach. The gains for engagement, security, and assurance justify implementation.
What steps will you take first to govern email deliverability in 2023?
