What is a transactional email? Definition & Intro

Single sign-on, password reset, welcome email, order confirmation — these all are transactional emails. Emails that are sent as a direct response to a user’s actions in an application, service, or website.

Transactional emails usually don’t receive much attention from business owners compared to marketing emails. But they are a crucial part of the customer experience. No one wants to wait for a password reset or SSO emails. A welcome email is the perfect opportunity to make a good first impression. A promptly delivered order confirmation email is great for trust and strengthening relationships.

I could continue listing the importance of transactional emails… Now the important step is to select the best transactional email service for your use case. I researched transactional email platforms and made a detailed comparison to help you choose.

TL;DR — Transactional email platforms overview

1. Sidemail — simplest yet complete service, best choice for SaaS

2. Sendgrid — most known all-in-one platform

3. Mailgun — old-school provider, previously very popular amongst developers

4. Postmark — solid delivery for SMBs knowledgeable about coding HTLM emails

5. Amazon SES — cheapest email provider, great for building robust systems

6. Bird (formerly SparkPost) — good solution for large enterprises

7. Mailchimp Transactional (formerly Mandrill) — easy pick for customers already using Mailchimp’s email marketing platform

Criteria for transactional email platform

The best transactional email service should match your use case as well as technical criteria.

• Reliability — Deliverability rates and speed are crucial for transactional emails. A good transactional email provider should deliver your emails quickly and reliably; every time and anytime.

• Good developer experience and smooth integration — Integrating transactional emails should not be a process that takes weeks of developers’ focus. Together with well-written documentation, clear instructions, industry-standard tips, and best practices, look for a transactional email service that will be a good partner for you and your development team, not be an obstacle.

• Clear and simple UI — The user interface of your transactional email platform should give you an overview of your emails, analytics, sufficient history of sending, data about deliverability, bounce rates, and spam complaints, and be intuitive and easy to manage.

• Customer support — When in need, you’ll appreciate having the possibility of reaching customer support who will help you resolve your questions and issues and be there to assist you further.

• Scalability — The chosen transactional email provider should allow you to flexibly upgrade or downgrade your plan if needed to send more emails without penalties. No waiting for the next billing period or the end of the contract.

• Premade email templates and design — No one wants to deal with broken HTML emails. Coding and testing templates that work well in all inboxes and devices is a daunting task. A good transactional email service will give you a head start by providing you with templates they have created and tested. All you need to do is select your branding like logo, font, colors, etc.

1.Sidemail

Sidemail is an all-in-one email delivery service mainly focusing on SaaS businesses. It’s built upon Amazon's robust architecture in combination with custom in-house configurations that ensure highly reliable and scalable email delivery.

Sidemail was founded in 2018 and is based in the EU. It’s one of the modern email delivery providers, yet covers all email delivery needs in one plan — transactional emails, email marketing, email automation, contact profiles management, and subscribe forms.

👍 Sidemail Pros

• Specialization in SaaS email delivery

• 5-star rated support

• Fast and reliable email delivery

• Integration under 30 minutes, simple instructions, intuitive UI

• All-in-one email platform – Sidemail is the most simple yet complete service.

• Premade email templates and an easy-to-use visual template editor

👎 Sidemail Cons

• Not offering a free plan

• “Different” approach – Sidemail’s main focus are SaaS companies, which makes a perfect solution for them, but it might not be suitable for others. If you are an offline business or need advanced functionality specifically for email marketing, other transactional email providers listed below might be a better solution for your case.

Sidemail pricing

Sidemail has monthly plans-based pricing with a free trial. Compared to other email providers on this list, Sidemail includes everything for delivering and managing emails in one plan – transactional emails, and newsletters, and email automation. Plans start at $19 per month.

2. SendGrid

Sendgrid is one of the if not the most known transactional email providers. The platform now also provides a broad spectrum of services for email marketing and email automation.

The company was founded in 2009 and is based in Denver, Colorado. As one of the oldest email providers, it’s used by large tech companies like Uber, Booking.com, Yelp, Spotify or Airbnb. In 2019 SendGrid was acquired by Twilio.

👍 SendGrid Pros

• One of the oldest and largest email delivery platforms

• Free plan with basic functionality

• Advanced features for testing and analytics

• Focus on large enterprises

• Broad-spectrum of tools and integrations not only for email delivery but also for SMS and WhatsApp

👎 SendGrid Cons

• Occasional issues with deliverability reported by a large number of customers

• Bad support experience reported by many customers even on paid add-on plans

• No premade email templates for transactional emails

• Only 3 days of sending history (for a 7-day history you have to upgrade to Pro or higher plan which starts at $89.95/mo)

• Complicated pricing with a lot of add-ons and extra fees for features

SendGrid Pricing

SendGrid has freemium pricing. The transactional email part of Sendgrid’s platform offers a free plan with 100 emails/day and limited functionality. Paid Essentials plan starts at $19.95 per month. The Pro plan which includes more than 1 team member, 7 days of data history, and 1 dedicated IP starts at $89.95 per month. If you want to send also marketing emails and set up email automation, you need to purchase a separate plan for that.

3. Mailgun

Mailgun is a transactional email platform — you can send, receive, and track transactional emails.

The company was founded in 2010 and is based in San Antonio, Texas. In previous years, Mailgun was a popular choice for developers as it is an API-first solution. Today, after a number of acquisitions in 2021, Mailgun is a part of Sinch company. Sinch company now also owns Mailjet which you can use for email marketing and email automation.

👍 Mailgun Pros

• Solid functionality for managing transactional emails

• 99.99% uptime SLA offered even on lower plans

• Inbound emails processing

👎 Mailgun Cons

• Uncertain deliverability results. Some customers reported issues with the deliverability and sending speed of their transactional emails.

• Mixed customer support ratings. In the last 3 years, there has been a notable rise in customers who report frustrating experiences with the Mailgun support team.

• Short message retention time. Mailgun stores messages by default only for 3 days. The period can be extended up to 7 days, but even that is a very short period compared to other providers.

• High learning curve and complicated integration for less experienced users

Mailgun Pricing

Mailgun has monthly plans-based pricing with a free trial. Mailgun plans start at $35 per month. If you want to send not only transactional emails but also marketing emails and set up email automation, you need to purchase a separate provider. Mailgun’s partnered company Mailjet offers plans for sending marketing emails and email automation, and their prices start at $25 per month.

4. Postmark

Postmark is a transactional email service based in Chicago, Illinois. Postmark was a bootstrapped company founded in 2009 by two co-founders. After years of running the company together, the founders decided to step away and sold Postmark to ActiveCampaign in May 2022.

👍 Postmark Pros

• Responsive support. Postmark is known for its good support experience.

• Solid delivery of transactional emails

• Unlimited team members

• Offers a complete self-serve option

👎 Postmark Cons

• No visual editor. Postmark does not have a visual editor for email templates. To create your templates, you have to write the code yourself. And coding emails that do not break is a tough and resource-expensive job.

• Not intuitive dashboard

• Support unavailable on weekends. The support team is available only between 3 am and 7 pm EST, Monday to Friday. No help outside of their business hours.

• Missing functionality for email marketing and automation. If you have a SaaS and need a service to cover all your email-sending activities, you have to find another email marketing and automation service.

Postmark Pricing

Postmark has monthly plans-based pricing with a free trial. 100 emails per month are free. Then, the paid plans start at $15 per month.

5. Amazon SES

Amazon SES (Simple Email Service) offers the most simple and low-level transactional email service. For its robust infrastructure and reliable delivery, it’s trusted by giants like Netflix, Reddit, and Duolingo. Amazon SES focuses on the technical side of email sending and offers only a very basic dashboard. As it is more a developer tool than an end-to-end product, it’s suitable for integrations with robust systems that need a lot of flexibility and for companies that can allocate a great amount of resources to developing their own email solution.

👍 Amazon SES Pros

• Cheapest email provider if you count sent emails only

• Robust architecture

• Extremely scalable

• Fast and reliable email delivery

👎 Amazon SES Cons

• Do-it-yourself approach. It requires a lot of manual effort from your site to get things running. Amazon provides you with low-level tools for email delivery, but all the integration, email template setup, troubleshooting, analytics, etc. is up to you.

• No support included

• No out-of-the-box features like template editor, premade templates, message history, email automation, or contact management

Amazon SES Pricing

Amazon SES has pay-as-you-go pricing. If you count emails only, it is the cheapest transactional email provider by far. 1000 emails cost $0.1.

6. Bird (formerly SparkPost, Message Bird)

Bird is CRM for marketing, services, and payments focusing on enterprise customers. The transactional email platform, formerly known as SparkPost was founded in 2008. In 2021 it was acquired by MessageBird being a part of a large platform that provides tools for sending transactional and marketing emails, SMS, and WhatsApp messages. In 2024 MessageBird rebranded to Bird.

👍 Bird Pros

• Background of a large platform providing not only email sending but also SMS and WhatsApp

• Focus on enterprise

👎 Bird Cons

• Complicated for “regular” businesses. Bird focuses on enterprise customers making a great solution for them, however, this approach is unnecessarily complicated for “regular” businesses. If you are not an enterprise, other transactional email services from this list will be a better solution.

• Poor customer support reviews

• Mixed deliverability and service quality reported by customers

Bird Pricing

Bird has contact-based monthly plans. In other words, the price for the service depends on the number of contacts you are targeting on a monthly basis. Bird pricing has numerous add-ons and extra feature fees. Prices in the table below are for basic sending emails only.

7. Mailchimp Transactional (formerly Mandrill)

MailchimpTransactional Emails, formerly Mandrill, is a paid Mailchimp add-on for sending transactional emails. For the purpose of this article, we’ll mainly use the former name Mandrill for the transactional part of the Mailchimp service.

In previous years, Mandrill was one of the most popular services for delivering transactional emails. In 2016 Mandrill merged with Mailchimp. Mailchimp became a main part of the platform and Mandrill with its transactional emails was offered as a paid Mailchimp add-on. In 2021 Mailchimp was acquired by Intuit and became a part of their global technology platform.

Since the Mailchimp + Mandrill acquisition, it seems like the transactional platform is not receiving much focus and development. Some former Mandrill customers report technical issues with the delivery and are migrating to other transactional email platforms. So if you need a tool with advanced features for email marketing, Mailchimp could be a good solution. But for the transactional emails, there are better platforms on this list.

👍 Mailchimp Pros

• Advanced email marketing features

• Generous free plan for email marketing

• Compatible with various web frameworks

👎 Mailchimp Cons

• Uncertain transactional emails. Since the Mailchimp + Mandrill acquisition, it seems like the transactional part of the product is not receiving much focus and development. Some former Mandrill customers report technical issues with the delivery and are migrating to other transactional email services.

• Marketing plan required to access transactional platform. If you want to send transactional emails, you need to purchase a marketing plan first.

• Not intuitive dashboard

• Only 30-day data history

• Previous data breach issues. Following the Intuit acquisition, Mailchimp suffered a number of data breach incidents in 2022 and 2023.

Mailchimp Pricing

Mailchimp is the most expensive email service on this list. It has monthly plans-based pricing with a free email marketing plan. If you want to send transactional emails, you have to pay for a Standard or Premium marketing plan + purchase Transactional email as an extra add-on. The Transactional email costs start at $20 per month.

Choosing a transactional email platform

I hope this overview of the transactional email platforms gave you a clearer understanding of what is the right option for you. Deliverability and reliability are crucial factors in choosing a transactional email service; however, your preferences and the specifics of your use case are also important considerations. If you have questions or need help with your email delivery, feel free to reach out at kristyna@sidemail.io.