For the last month or so, I have spent my days testing popular transactional email services. After experimenting with dozens of tools, I selected 7 best-performing providers.
In this article, you’ll learn which comparison criteria I used and how you can use them. (Go check the methodology.)
Plus, I share detailed deliverability results of the comparison to help you make an educated decision. Anyway, let’s start with the summary of 7 best transactional email services.
7 Best transactional email service providers
- Mailtrap for developers and marketers who need a platform for marketing, mass, and transactional emails with industry-best analytics.
- SendGrid for businesses of all sizes looking for a scalable solution.
- Mailgun for businesses looking for a two-in-one solution for transactional and marketing services;.
- Brevo (formerly Sendinblue) for individuals and small to medium businesses looking for versatile integration options, not just API or SMTP.
- Amazon SES for businesses with strong dev teams looking for an affordable solution and already using AWS infrastructure.
- Postmark for businesses looking for a volume-based pricing structure, not a feature-based one.
- Mailchimp Transactional Email (formerly Mandrill) for businesses already using Mailchimp as their marketing platform.
| Product | Free plan | Pricing |
| Mailtrap | 1000 emails/month | From $20 |
| SendGrid | 100 emails/day | From $19.95 |
| Mailgun | 100 emails/day | From $15 |
| Brevo | 300 emails/day | From $15 |
| Amazon SES | 3,000 message charges/month (for the first 12 months) | $0.10 per 1,000 emails (pay-as-you go) |
| Postmark | 100 emails/month | From $15 |
| Mailchimp Transactional Email* | No (500-email free trial) | From $20 |
*Mailchimp Transactional Email isn’t a standalone product but an addition to Mailchimp Marketing, so you’d have to account for its pricing, which starts from $20.
Transactional email service providers comparison criteria
Quite a few things affect the efficiency of a transactional email service. I curated a detailed overview of all the features you must account for. To make it more digestible, I categorized everything in order of importance, starting with email infrastructure.
Email infrastructure
Three aspects of email infrastructure largely influence the performance of your emails. Given that user-triggered (transactional) emails are expected to be almost instant, you need to pay close attention to the following.
Deliverability
Opt for an SMTP service that enforces key authentication protocols like DKIM, SPF, and DMARC. Also, look for advanced features that can significantly improve email performance. These include:
- Bounce tracking
- Spam complaint monitoring
- Inbox placement insights
- Webhook-based event notifications
To the above, a dedicated SMTP stream for bulk emails can also contribute to higher deliverability rates and better inbox placement. However, your sender reputation remains a critical factor—check the details in our dedicated guide.
More importantly, we wanted to assess the deliverability performance of various SMTP providers fairly. So, Mailtrap teams ran independent tests on the top five providers listed in this article. For all, the conditions and methodology were as follows:
- A free-tier subscription
- A shared IP environment
- Identical email templates across all providers
- Seed testing for accurate deliverability tracking
Here are the summarized test results:
| Service provider | Inbox placement test results |
| Mailtrap | Inbox: 78.8% Tabs: 4.8% Spam: 14.4% Missing: 2.0% |
| Amazon SES | Inbox: 77.1% Tabs: 1.9% Spam: 20.0% Missing: 1.0% |
| Mailgun | Inbox: 71.4% Tabs: 3.8% Spam: 23.8% Missing: 1.0% |
| SendGrid | Inbox: 61.0% Tabs: 1.0% Spam: 17.1% Missing: 20.9% |
| Postmark | Inbox: 83.3% Tabs: 1.0% Spam: 14.3% Missing: 0.9% |
Check our deliverability comparison guide for more information on the testing methodology and the results.
Pro Tip: The cost of undelivered emails can be high, particularly if you send them at scale. We have done a deep-dive into the topic, providing all the numbers and a top-level overview. Check the blog post here (p.s. There’s a bonus video where our product lead Oleksii discusses the topic with Constantin von Hoffman from MarTech.)
Reliability
To evaluate reliability, you need to consider the services’ uptime. Most offer a public status page displaying real-time uptime metrics, such as Mailtrap’s status page or Mailgun’s status page. Some providers go further by offering service-level agreements (SLAs), ensuring uptime of at least 99%.
Another key factor is infrastructure redundancy. It refers to duplicating critical components across networks, data centers, and IT environments to prevent service interruptions. To assess this, review the provider’s documentation for details on:
- Datacenter distribution – A geographically dispersed network ensures better resilience.
- Backup mechanisms – Look for mentions of failover systems or automated backups.
- High availability measures – Load balancing and database replication help sustain uptime and ensure rapid email delivery.
- Security standards compliance – Certifications such as ISO 27001 or SOC 2 indicate adherence to backup and disaster recovery best practices.
Note: For security reasons, some service providers won’t be overly transparent about infrastructure redundancy (except for security standards compliance). But that’s not a negative thing by any means, and you can always ask for the information.
Scalability
A scalable email service is essential for maintaining fast delivery speeds and preventing downtime, particularly when sending emails at a volume. The same goes if you experience a sudden spike in demand for transactional emails (e.g., exponential signup growth 😀).
To stress, if the service isn’t scalable (and all in this article are), the delivery bottlenecks may turn growth into churn. Plus, it’ll negatively impact your business as a brand.
So, here’s how to evaluate a provider’s scalability:
- Check volume limits under pricing plans – Besides the limit for a specific plan, the service should also account for overages, typically between $0.50 and $2,00 for every 1000 emails.
- Assess dedicated IP options—If needed, confirm whether the provider offers dedicated IPs and check the associated costs. Typically, “Pro” and higher plans should include the dedicated IP. But a dedicated IP doesn’t make sense if you send less than 100K emails a month.
- Investigate past performance issues – Visit the status page and review logs for incidents like “degraded performance” or “delayed email delivery,” which may suggest scalability challenges under heavy loads.
- Review API rate limits – If you’re sending emails via API, verify the rate limits. A small sender typically needs 1-5 RPS, whereas enterprise senders require at least 500-1,000 RPS to handle mass email campaigns efficiently.
Pricing
Pricing is usually based on the number of emails you send and the number of contacts you have. However, there are additional limitations, especially on lower plans, which may involve a lack of automation and segmentations, lower data retention, etc.
You should carefully assess your needs, the current tech stack, and the desired email workflows to determine which plan corresponds best with your business. Still, I want to give you some numbers and ballpark estimates so you can get a more holistic picture of how much you’d play.
A well-designed pricing structure allows for gradual scaling without forcing users to leap into top-tier plan. For instance, if an SMTP provider only offers a Basic plan at $10/month for 1,000 emails and a Business plan at $100/month for 100,000 emails, users needing 10,000 emails might be stuck with an oversized, costly plan.
Beyond pricing, it’s essential to calculate the cost per successfully delivered email rather than just the advertised price per thousand emails. Take deliverability rates into account. For instance, if Mailtrap reports a 91% deliverability rate and charges $1.50 per 1,000 emails, you can use this formula to determine the actual cost:
This approach ensures you’re paying for real email performance, not just theoretical sending capacity.
Transactional email sending
One of the first things I check is the availability, or lack thereof, of robust APIs and SDKs across multiple programming languages, such as Python, PHP, and Node.js.
I always review the API documentation to ensure it’s well-structured and easy to follow. I also explore online discussions and reviews to see what users are saying about deliverability and ease of integration.
But why should you care about APIs?
APIs enable programmatic automation, allowing you to integrate email sending directly into your app or service. In turn, you ensure user-triggered emails work well across all email clients, which helps build trust and strengthens your brand’s image.
In addition, make sure to check the following features:
- Advanced analytics and deliverability insights – Offers real-time stats and alerts on email performance, helping you track engagement, identify deliverability issues, and fine-tune transactional emails.
- Email log retention – Access to a longer sending history (15-30 days) is valuable for auditing, troubleshooting, and analyzing email trends.
- Pre-built transactional templates – A convenient feature for quickly personalizing emails with dynamic content, variables, and images, streamlining the email creation process.
- SMTP integrations – In addition to APIs, the service needs to have well documented SMTP workflows. Ideally, you’ll get ready-made code snippets for easier integration.
Tip: This article solely focuses on transactional (user-triggered) emails, but most platforms also provide email marketing services. If you want more information on that, check the articles below:
Security and compliance
You need to prioritize security and compliance to protect sensitive data and maintain customer trust. Otherwise, compliance and security lapses can turn into multi-million-dollar fines. To avoid that, evaluate these:
- Industry-recognized certifications: Opt for providers that have achieved certifications such as ISO/IEC 27001, which sets international standards for information security management systems, and SOC 2 Type II, which evaluates the effectiveness of security controls over time.
- Data protection regulations: Ensure the service complies with relevant data protection laws, including the General Data Protection Regulation (GDPR) for EU residents and the Health Insurance Portability and Accountability Act (HIPAA) for healthcare data in the U.S.
- Advanced security features: Look for end-to-end encryption to safeguard data during transmission and in storage. A welcome addition are robust access controls to restrict unauthorized access, and regular security audits to identify and address vulnerabilities.
AI, email automation, and integrations
AI integration, email automation, and system integrations can boost your email operations, making it easier to adapt the messaging to recipients. Here’s how to assess them:
- AI-powered features: Look for services incorporating artificial intelligence to optimize email delivery and content. For instance, Mailtrap’s email builder has a host of AI-enhanced tools to optimize subject lines, content, email format, and more.
- Email automation: Effective automation tools are crucial for timely and relevant customer interactions. Providers like SendGrid offer comprehensive automation capabilities, enabling businesses to set up triggers and workflows that streamline communication processes. This is typically without extensive coding.
- System integrations: Ensure the email service can seamlessly integrate with your existing platforms, such as CRM systems, e-commerce platforms, or content management systems. Mailchimp, for example, has expanded its partnership with Canva, allowing users to integrate Canva-created content directly into Mailchimp.
User experience
It’s tricky to objectively assess user experience since it may depend on personal preferences and the experience of the professional responsible for integrations. Nonetheless, I identified two universal characteristics that should help you estimate how user-friendly a service is.
- Intuitive interface: A user-friendly dashboard simplifies the management of email campaigns, allowing team members to navigate and utilize features efficiently. For instance, at Mailtrap, we doubled our efforts to put all the critical data under one helicopter-view dashboard with one-click drill-down reports and easy access to auxiliary features.
- Comprehensive onboarding: A transactional email service needs to provide detailed yet straightforward onboarding processes, including tutorials and documentation. This can significantly speed up the setup and integration phases. At Mailtrap, for example, you get an onboarding wizard, detailed integration documentation, and video tutorials.
Customer experience
To effectively assess customer experience, consider the following:
- User reviews: Websites like G2 provide real, up-to-date product reviews from verified users, helping you gauge customer satisfaction and identify potential issues.
- Expert evaluations: Resources such as niche blogs offer detailed evaluations and app testing, giving you hands-on insights into the best transactional email services available.
Community discussions: Participating in forums and online discussions can reveal common experiences and tips from other businesses, giving you a practical understanding of what to expect from the service.
Best transactional email service provider: Mailtrap Email Delivery Platform
Disclaimer: The prices and product ratings are up-to-date at the time of writing and could be different when you’re reading this blog post. Also, all the included prices are for monthly subscriptions and can differ for annual plans.
Mailtrap is an email delivery platform that has both Email Sending and Email Testing solutions. For this blog post, I’ll focus on Email Sending.
Email Sending is an email product with high deliverability rates by design. It has Email API and SMTP Service and ready-made SDKs for Node.js, Ruby, PHP, Python, and Elixir.
Creating the account is quite straightforward. You just go to the signup page, choose the registration method, and fill out the empty fields.
Once the account was ready, I went to Sending Domains to add and verify my domain. This step is necessary to confirm the ownership of the domain and set up authentication protocols. The latter helps with deliverability (and is now a requirement from Google and Yahoo!).
Read this article or watch the in-app video for detailed instructions on adding and verifying the domain.
After the domain was verified, I was able to start sending the emails.
You have SMTP and API integration options with sample configurations for popular programming languages and frameworks. Check out this playlist to learn how to integrate Mailtrap and send emails with API or SMTP.
Mailtrap also has migration guides if you’re migrating from another solution. You can check out how to migrate from SendGrid, Mailgun, Mailchimp Transactional Email, and Amazon SES. To migrate smoothly and gradually, you can use the ActionMailer Balancer gem if your app is built in Ruby.
One of the most important and useful features is that Mailtrap offers separate streams for transactional and bulk emails. This helps maintain high deliverability rates.
Mailtrap also has transactional email templates. These can be created and stored within the platform and referenced later through API calls. Templates operate on the handlebars engine and support variables.
Another handy feature is actionable analytics with drill-down reports and helicopter-view dashboards. The drill-down reports are available for email categories and mailbox providers. You can filter the stats based on categories, providers, domains, and streams.
Additionally, you can track unique open rates, delivery rates, click rates, bounce rates, and spam complaints.
Features
- Separate streams for transactional and bulk emails
- SMTP, API, and SDKs
- In-depth stats with actionable analytics
- Transactional email templates
- Up to 30 days of email logs
- Deliverability alerts to catch unexpected sending issues
- Suppression management
- Webhooks
- Dedicated IP addresses with automatic warmup for high-volume senders
- Email Campaigns
Pros
- Supportive and helpful customer service regardless of the pricing plan
- 99.9% server uptime
- Clear and intuitive in-app interface
- High deliverability rates
- Easy-to-read dashboards
- Essential features available for all pricing plans
- Can be scaled by changing the plan if your email volumes increase over time
Cons
- Lacks plugins and ready-made integration options for non-dev teams
Pricing
- Free tier: 1,000 emails/month
- Paid plans: from $10 for 10,000 emails/month
- Additional 1,000 emails: $1 and less.
Visit the pricing page for more details on available plans and features.
SendGrid
SendGrid is among most popular transactional email service providers. They offer an Email Marketing tool suitable for diverse teams that need marketing automation, segmentation, etc.
SendGrid’s Email API, on the other hand, is geared toward developers (similar to most transactional service providers). But note that the documentation can be hard to understand even with technical expertise.
The good thing about SendGrid Email API is its analytics feature. There’s hardly anything you can’t track and analyze with this platform. However, it has a flip side – a steep learning curve while setting up and understanding all the dashboards and stats. It also lacks a unified dashboard showing an overall overview of the email performance. This makes the analytics somewhat scattered.
Also, some essential features are reserved only for higher-paying plans. For example, the support team’s response time and the type of support vary by plan.
Now, it may sound a bit selfish, but if you’d like a deep-dive comparison of SendGrid vs Mailtrap and other competitors click here ◀️. And if you’re considering migrating from SendGrid, here’s a direct comparison of only SendGrid and Mailtrap.
Features
- SMTP, API, and third-party integration options
- Diverse dashboards and stats for in-depth analytics
- Email validation API
- Dynamic email templates with drag-and-drop and HTML editors
Pros
- Easy to connect to other platforms and services
- Comprehensive integration guides, tutorials, and API documentation
- Continuous sender reputation monitoring
Cons
- Some of the essential features reserved for higher-paying plans
- Slow support
- Occasional downtimes
Pricing
- Free tier: 100 emails/day
- Free trial: Yes
- Paid plans: from $19.95 for 50,000 emails/month
- Additional 1,000 emails: $1.33 and less
Mailgun
Mailgun allows you to send, track, and optimize different types of transactional emails and marketing campaigns.
They recently introduced a product suite consisting of Mailgun Send, Mailgun Optimize (email deliverability tool), and Mailgun Validate.
Here, I focus on Mailgun Send, which allows API or SMTP methods with instructions and code samples to make the integration process easier.
One of Mailgun Send’s highlights is the intuitive analytics dashboard. Users can also create and store templates on the platform with a drag-and-drop and/or HTML editor. I found the templates a bit limited for marketing campaigns, but they were sufficient for simple order confirmation emails or other transactional notifications.
Another useful feature is the option to switch between the US and EU regions, each with different SMTP and API endpoints (available in paid plans).
Similar to Mailtrap, Mailgun Send requires technical expertise to set up. However, I found Mailtrap’s docs easier to understand and follow. Check out this blog post for more comparisons of Mailgun and its competitors.
Features
- Send time optimization
- Email validation (add-on for Foundation plan and included in Scale)
- API and SMTP integration, as well as third-party integrations with CRM, CMS, E-commerce, and other platforms
- Email templates
- Email tracking and analytics
Pros
- The ability to validate emails without switching to another platform
- A wide selection of third-party integrations
- High deliverability rates
- Allows for (and recommends) using subdomains for different types of emails
Cons
- Slow support
- You can’t search logs by email content (searching by tags is supported, though)
- The platform has several bugs (probably due to the addition of new features)
Pricing
- Free tier: Yes (100 emails/day)
- Free trial: 30 days (for the Foundation plan), 50,000 free emails
- Paid plans: from $15 for 10,000 emails/month
- Additional 1,000 emails: from $1.80 to $1.10.
Brevo (ex Sendinblue)
Brevo (formerly Sendinblue) is a CRM suite that has a Marketing Platform, Conversations, Sales Platform, and Transactional Email products.
Integration options include SMTP and API. You’ll find examples for Postfix and PHP in the wizard itself. Also, Brevo Transactional Email has official SDKs for multiple languages and frameworks.
Pro Tip: Brevo allows you to send emails without adding or verifying the domain being sent. You can use a free email address. However, I strongly recommend against it as it will negatively impact your deliverability, especially with Google and Yahoo.
So, if you choose Brevo as your transactional email platform, make sure you add a sending domain and authenticate it with DKIM, SPF, and DMARC.
The interface is really user-friendly, and so is the documentation. Yet, some parameters are located in the profile menu, not under Transactional as I expected. This can be a bit confusing when you’re getting started.
With that being said, Brevo Transactional Email is an affordable solution, especially if you’re already using Brevo as your marketing tool.
Features
- Transactional email templates with code and drag-and-drop editors
- Email tracking and analytics
- SMTP relay, API integration, and plugins
- Customized log retention
Pros
- Volume-based pricing structure with all the features available in all tiers
- Easy to set up and use
- Generous free tier
Cons
- Limited design options for email templates
- Some essential features are hidden in the menus
Pricing
- Free tier: 300 emails/day
- Free trial: No
- Paid plans: from $15 for 20,000 emails/month for Transactional Email separately, but you can also send transactional emails with email credits in marketing plans.
- Additional 1,000 emails: N/A
Amazon SES
Amazon SES (Simple Email Services) is one of the most cost-effective options for sending transactional emails. It offers a specific free tier and is particularly handy for those already using AWS infrastructure and EC2.
For the first 12 months, users get access to 3,000 so-called message charges for free. These “charges” include inbound and outbound emails and Virtual Deliverability Manager. After the free trial, you’ll pay $0.10 per 1,000 emails (additional fees apply).
Note: Even with the free trial, you pay data transfer fees and any add-ons you purchase. Their pricing structure is generally pretty nuanced. So, I suggest checking Amazon’s SES pricing page to determine exactly how much you’d pay.
SES offers a dedicated IP (for an additional fee), reputation metrics, basic analytics, suppression management, and email templates. It’s reliable for transactional messages, but AWS is definitely geared for technical teams looking for basic email functionalities.
If you’d like to know more about Amazon SES and its alternatives, read this blog post.
Features
- SMTP server, robust API, and SDKs
- Reputation monitoring
- Virtual Deliverability Manager with dashboards and optional automatic optimization
- The ability to send bulk and transactional emails
- The ability to choose the region for the servers
Pros
- More affordable compared to its competitors
- Robust security features and spam protection
- Highly scalable
- Supports inbound messages
Cons
- Slow customer service
- Analytics are hard to set up
Pricing
- Free tier: 3,000 message charges/month (for the first 12 months)
- Free trial: No
- Paid plans: Pay-as-you-go pricing model with $0.10 per 1,000 emails (additional fees apply).
Postmark
Similar to Mailtrap, Postmark is a platform that enables users to send bulk and transactional emails. They, too, have separate streams for both.
While Postmark’s interface is quite simple, the naming of the features is a little different from other platforms. For example, the default page is Servers, which act as projects without connection with actual servers. This can be a bit confusing in the beginning, but they do have an explanatory video and a getting started guide.
You’ll find three streams within each Server (or project): Broadcast (bulk), Inbound, and Transactional.
Transactional Stream comes with SMTP and API integration, topped with official and community libraries for various programming languages and frameworks. Postmark also offers plugins and various integrations through Zapier.
One of Postmark’s notable benefits is its pricing structure. It charges you based on the number of emails you send, not the specific features. However, keep in mind that dedicated IPs should be purchased separately if needed (they cost $50 per IP per month and are available for users sending more than 300,000 emails/month).
Features
- Sandbox server for testing their bounce API
- Separate streams for transactional and broadcast emails
- Comprehensive and well-structured documentation
- Different types of webhooks
- Suppression management
- Analytics
Pros
- High deliverability rates
- Wide selection of libraries and integration options
- Email templates
- Well-documented API
Cons
- Dedicated IP isn’t included in the pricing
Pricing
- Free tier: No
- Free trial: Yes
- Paid plans: $15 for 10,000 emails/month
- Additional 1,000 emails: $1.8 and less
Mailchimp Transactional Email (formerly Mandrill)
G2: N/A ⭐ Capterra: 4.5 (the whole platform) ⭐
Mailchimp Transactional Email isn’t a standalone tool but rather a transactional-oriented add-on. It’s only suitable for Mailchimp users as it can’t be used without a Mailchimp Marketing Platform subscription (Standard, Premium, or Legacy).
The setup process is similar to other transactional providers, but the UI is a bit outdated. Regardless, Transactional Email still has decent analytics, inbound routing, webhooks, suppression management, and customizable settings.
While I wouldn’t recommend this tool if you only need a transactional email delivery service, it performs quite well as a Mailchimp add-on. Only note that if you send user-triggered emails at scale, the cost can build up fast.
Features
- SMTP and API integration
- Customizable sending domain settings
- Analytics with the ability to create comparisons
- API logs
- Webhooks
- Suppression management (Rejection Lists)
Pros
- Test mode to test the setup before sending emails in production
- Email alerts for reputation drop or webhook failure
- Sender reputation tracking
- A/B testing (Split Tests) for transactional emails
- Code editor to create email templates
Cons
- Can’t be used without Mailchimp Marketing Platform
- Costlier compared to its competitors
- Outdated UI
Pricing
- Free tier: None
- Free trial: Yes (500 emails)
- Paid plans: $20 for 25,000 emails/month (has a block-based pricing structure, price per block is lower for high-volume senders) + Marketing Platform subscription (from $20)
- Additional 1,000 emails: N/A
Note: Most reviews are for Mailchimp overall, not specifically for Transactional Email.
Wrapping up
Now you have the information and resources to choose the best transactional email service. Apart from the defined criteria, you may also want to consider the following factors:
- Payment preferences. Do you prefer to have a monthly plan or a pay-as-you-go option? Are you looking for monthly or annual billing?
- Types of emails you’ll be sending. Will you be sending only transactional emails or bulk and marketing emails as well? For the former, choose a platform that focuses on transactional emails. For the latter, consider providers that offer both, especially the ones combining the three within one plan or flow.
And before you send those emails to recipients, don’t forget to test them with a dedicated tool such as Mailtrap Email Testing. With its help, you can easily validate HTML/CSS, check the spam score, or test the email-sending functionality of your app.
Once the tests are completed, pair it with Mailtrap Email Sending to test, send, and control your infrastructure, all in one place.