In the sea of email marketing newsletters, transactional emails are often an overlooked opportunity—they aren't the most exciting emails a customer receives from you, but they're some of the firsts, and they have incredibly high open rates. Way higher than marketing emails.

An order confirmation, a welcome email, a dispatch update, and even a new device login—they're all opportunities to build and strengthen customer relationships. 

If a customer has ordered from you, maybe they're interested in another one of your products. If they're resetting their password, perhaps they're logging in after a long time and need a product tour refresher. All transactional emails are an occasion to deepen customer trust and share personalized offers.

I've been researching, testing, and writing about email marketing software for the last five years. And I know the decision to choose an email tool can be time-consuming. To update this list for this year, I spent several weeks researching and testing over two dozen transactional email apps. Based on that experience, here are the five best.

The best transactional email services 

• SendGrid for transactional emails and email marketing in one

• Mailchimp Transactional Email for Mailchimp users

• Postmark for quick email delivery

• MailerSend for building branded transactional emails with ease

• ZeptoMail for excellent 24/7 phone support

What makes a great transactional email service?

Picking a tool to send transactional emails is tricky—there are tons of options offering similar services and competitive pricing. I started by figuring out what the essential features were for apps in this category. Here's what I looked for during my evaluation of transactional email providers:

• Value for money. Transactional email tools are a heavy investment. It's essential to get a feel of the app before purchasing, so the best transactional email apps aren't just competitively priced but also include a free trial or a cheaper plan with fewer features to test out the features without an annual financial commitment.  

• Ease of setting up. There's nothing more frustrating than signing up for a transactional email app, making an account, and then being unable to figure out how to configure your domain. Your team—developers or not—should be able to easily log in to the app and set it up for action. 

• Customer support. Even the experts need help sometimes. Success with a transactional email app means getting quick and reliable support—whether that's in the form of live chat, email, or phone. The best tools also have an extensive and updated knowledge base so you can help yourself when possible. 

• Customizing the emails. The days of boring and bland transactional emails are long gone. Customers now expect branded transactional emails with your logo, aesthetic designs, and overall an amazing experience. The best transactional emails make it easy for you to design and brand your emails.

• Deliverability. There's nothing worse than a customer receiving their dispatch status email in spam, or worse, not receiving any update at all. The ideal transactional email app has excellent deliverability—ensuring you land in your customers' inboxes on time. 

To find the best options, I signed up for free trials of all the apps that met my criteria and tested them. I added contacts, drafted an email, and sent two or three test emails for each app—unless their domain verification process made it impossible to move ahead with testing. Along the way, I took notes on everything I encountered—what I liked and what I didn't like.

I also read user reviews to better understand how the various features held up over a period of several months or years, versus just a few weeks. For example, I checked to see if there was overwhelmingly negative feedback about deliverability or bounced emails when the volume of emails increases as a business scales. Once I'd narrowed down the list, I tested the shortlist again, even more in-depth, to be sure each service lived up to its unique selling point. And that's how I landed on these five apps.

The best transactional email services at a glance

Best transactional email service for transactional emails and email marketing in one

SendGrid

SendGrid pros:

• Setting up is a breeze

• Drag-and-drop feature to create and design emails easily

SendGrid cons:

• It might be expensive to scale after you cross the 200K email mark—price jumps from $89.95/month to $249/month

If you want to manage your transactional emails and marketing emails under one roof, SendGrid is the way to go. Transactional emails are at the core of SendGrid's business, so it's no surprise it's a killer in this domain. And it stacks up really nicely against some other big names.

For example: SendGrid outshines Mailchimp with its intuitive email editor as well as its deliverability insights. (SendGrid even offers deliverability consulting if you need additional support.) SendGrid offers an expert insights report, deliverability metrics, category comparisons, and more. And because SendGrid is a transactional email app first and foremost, it has all the features—whereas the standard Mailchimp UI and data aren't present in Mailchimp Transactional Email. Similarly, SendGrid outshines other apps like Sendinblue with its API integrations and support for multiple frameworks like Java, PHP, Go, Python, and C#.

SendGrid's email templates are great for customizing and branding emails. There are a lot of options to add your brand logo, alter the design, and even add your own code. But most of the email templates are a better fit for marketing emails than transactional emails.

I was also impressed by their email testing—you can do inbox rendering and test your emails for how they look and deliver on different devices. But this ease of use comes with a trade-off: SendGrid probably wouldn't be your ideal choice of email marketing app if you're looking for complex automation and workflows.

The free plan gets only ticket support. As you move up the plans, you also get a chat support option. But only the most expensive plans (Pro and Premium) get phone support.

The email testing capabilities, combined with SendGrid's comprehensive analytics, make it super easy to continually improve your emails based on feedback. So if you want to do your email marketing and transactional emails in one place—without sacrificing the quality of the transactional side of things—SendGrid is my pick. (You can also purchase marketing and transactional email services separately if you don't want to commit to both services off the bat.)

You can also automate SendGrid with SendGrid's Zapier integrations to do things like automatically sending transactional emails based on new form submissions or spreadsheet updates. Here are a couple of examples.

SendGrid pricing: Free for up to 100 emails/day. The Essential plan begins at $19.95/month and includes 50,000 emails, guaranteed response time on ticket and chat support, and more.

Best transactional email service for Mailchimp users

Mailchimp Transactional Email

Mailchimp pros:

• Excellent deliverability

Mailchimp cons:

• No email customization options (unless you know how to code)

The email marketing leader Mailchimp designed Mailchimp Transactional Email (formerly Mandrill) as a paid add-on, so any Mailchimp user has a viable option for sending transactional emails straight from Mailchimp. So if you're using Mailchimp as your email marketing tool, there's no reason to use a different app for transactional emails. (I wouldn't recommend it if you aren't already using Mailchimp because you have to create a Mailchimp account to use Mailchimp Transactional Email—you can't purchase just the latter like with SendGrid.)

Mailchimp has robust API documentation—which was helpful for me as I navigated the system—but you might still need help from your engineering team to set up everything. It's not easy to just log in and hit the ground running. But there's a lot of room for setting up rules and optimizing customer journeys. For example, you can set up a  "Reminder" email sequence at regular intervals for any email subject line that includes the word "event" (to nudge your subscribers to join an event they've signed up for).

There's nothing groundbreaking in the customizations department—unless you know how to code. The text email builder doesn't have any drag-and-drop options to customize your emails with images, logo, and other forms of branding.

The main problem I had was that, in order to send an email, you need to configure DKIM and SPF settings, which require you to update the TXT records with your domain host at the backend. It's a few extra steps, and it's complicated if you already have an SPF record added to your domain and need to add a second one for Mailchimp. That's the situation we were in, so I couldn't actually send a test email—but if you already trust Mailchimp to send your emails, you'll be able to rely on Mailchimp Transactional Email too.

Mailchimp also has a unique pricing structure: instead of the classic monthly plans, you can purchase "blocks" based on the number of emails you need. For example, if you need 10,000 emails for one month, you'll purchase one block at $20. This option is great to have if you have seasonality in your business and won't need the same number of emails each month.

But remember: a con of this unique pricing method is the purchased blocks don't transfer to the next month if left unused. So if you purchased a block for 10,000 emails but ended up using only 8,000, the remaining 2,000 emails would be wasted because you couldn't carry them to the upcoming month.

You can automate Mailchimp Transactional Email with Zapier, connecting it to all the other apps in your stack. That way, you can do things like automatically receive Slack notifications for every new bounced transactional email or send template Mailchimp emails when new Mailchimp Transactional subscribers are added. Get started with one of these pre-built templates.

Mailchimp Transactional Email pricing: Free for new users for up to 500 emails. You can send 1 to 500,000 emails by purchasing 1-20 blocks at $20/block (each block is a credit for 25,000 emails). Enter your estimated number of emails per month in their pricing calculator to get an accurate cost.

Best transactional email service for quick email delivery

Postmark

Postmark pros:

• Super fast and reliable email delivery

• Combined automations with ActiveCampaign

Postmark cons:

• You can't customize your emails unless you know how to code

Postmark specializes in only one service—transactional email—and does it well. It goes back to basics, focusing on core email sending. 

Where Postmark stands out is its speedy email delivery: it aims to deliver all your emails within 10 seconds after you press send (they have a separate message stream for transactional emails to ensure timely delivery in the primary inbox). I was able to verify this while testing—the email I sent was delivered within 7 or 8 seconds of sending. 

I found the setup instructions to be pretty straightforward. You simply choose the language or framework you want to use and get instructions for setting up. I chose to set up via the WordPress plugin on my website, and it was done in under 10 minutes. And their knowledge base felt much more approachable than the other apps on this list. Postmark also has several useful email templates available for specific use cases like welcome emails and password reset emails.   

Like with Mailchimp, you need to know how to code if you want to brand your transactional emails. There aren't any drag-and-drop features to easily add images, videos, and other forms of multimedia. And unlike the other apps on this list, Postmark doesn't offer many fancy bells and whistles. But if you need a reliable service provider that puts transactional email first, Postmark is a great choice. 

One last note: ActiveCampaign recently acquired Postmark, and while Postmark remains available as a standalone product, ActiveCampaign users can now see a full picture of their customers and use just one application for all their email needs. You can even connect your ActiveCampaign and Postmark accounts and set up a combined automated email sequence. For example, if you want to send a relevant marketing email to someone after they purchase a product from you, you can do that easily by connecting your ActiveCampaign and Postmark account.

You can do even more with your transactional email by using Postmark's Zapier integrations to do things like getting notified via Slack whenever an email bounces and even resend it. 

Postmark pricing: Free for up to 100 emails per month. Paid plans begin at $15/month for 10,000 emails. (Unused emails don't roll over to the next month, just like Mailchimp.) If you're a bootstrapped company, Postmark also offers a $75 account credit to help you reduce your email costs.

Best transactional email service for building branded transactional emails with ease

MailerSend

MailerSend pros:

• Lots of options to customize and brand your emails

• Email verification feature to remove fake, misspelled, or inactive emails

MailerSend cons:

• Domain verification can take longer than expected

MailerSend is a dream come true for non-tech teams and developers. Its drag-and-drop email builder is super intuitive, but there's also a rich text editor and HTML for developers who need it. There are also several transactional email templates, so you never have to start from scratch. I opted for the drag-and-drop email builder and found 30 templates—ranging from simple shipping notifications to complex ones like order-on-hold. 

I tested the invoice receipt email template, and it was really quick to customize: adding and deleting various content blocks (social links, image, etc.), changing the background, modifying sections—it all took less than 15 minutes (given I had every detail and attachment available on my desktop). It has a lot of features—so it can get overwhelming. But once you get the hang of it, MailerSend is one of the best tools for email design on this list.

The whole setup process was similarly easy: there are even domain authentication instructions that pop up as a chatbox as you finish setting up. I found that particularly helpful because there was a guide available for various domain providers, including GoDaddy, Wix, Namecheap, and more—meaning a user doesn't have to hunt for other resources outside the app. But even if something doesn't work, there's email support in the free plan and chat support in the paid plans. There's no phone support in any plan.

They also have an email verification feature that allows you to run a fine-toothed comb through your email list and remove any emails that are misspelled, fake, spam, or simply inactive. This could be immensely helpful in validating your email list—and by extension, boosting your sender reputation and deliverability rate.

You can use MailerSend's Zapier integrations to automate your transactional emails. Get Slack notifications for hard bounced emails, send an email for refunded PayPal sales, or anything else you can think of to connect all your apps.

MailerSend pricing: Free for up to 3,000 emails per month. The premium plan begins at $30/month for 50,000 emails; $0.90 for an additional thousand emails.

Best transactional email service for excellent 24/7 phone support

ZeptoMail

ZeptoMail pros:

• 24/7 email and phone assistance

• Pay-as-you-go option

ZeptoMail cons:

• Setting up isn't very smooth (you might need some assistance) 

ZeptoMail is like SendGrid with better support. It has 24/7 email and phone call assistance in all its plans (even the free one!)—which is an absolute standout in the transactional email service market. It's part of the Zoho suite of apps, which is known for its affordability.

Another thing I loved in ZeptoMail is the email templates. There are a ton of options to choose from, and they're super easy to customize. There's a drag-and-drop builder like MailerSend (although not as thorough). I'd say my experience within the app was even slightly better than SendGrid. 

Setting up is easy, but not as smooth as Postmark. You might need some tech assistance (which is great with their 24/7 phone support!) initially to set up your SMTP or API. But after this friction, the app is easy and intuitive to use. You can select multiple mail agents to send your transactional emails.

The deliverability is ok—it wasn't very quick, but the email landed in my primary inbox, so that's a win. 

I also like that ZeptoMail has a pay-as-you-go option. It's beneficial if you have seasonally high requirements (like during the holidays). The credits you purchase are valid for six months, so there's enough time to utilize them all and not pay for more emails than you're using.

To do more with ZeptoMail, connect it to Zapier, so you can do things like send Slack messages for new email activities or email bounces. Here are a couple of other examples to get you started.

ZeptoMail pricing: Free for up to 10,000 emails. You can purchase one credit for £2 (1 credit = 10,000 emails). Each credit is valid for six months.

Which transactional email app should you use?

If you're already using an email marketing tool that offers a transactional email service, it's worth starting there. If that doesn't meet your needs, you'll want to look for an app whose primary focus is transactional email—give the apps on this list a try, and see which fits your workflow best.

No matter which app you choose, you want your emails to be as effective as possible. Here are a few ideas to level up your transactional email app with automation. Then take a look at 3 ways to nurture customer relationships with email automation. 

Related reading:

• SendGrid vs. Mailchimp: Which is best?

• Email marketing automation ideas

• The best Mailchimp alternatives (free and paid options)

This article was originally published in January 2015 by Matthew Guay. The most recent update was in March 2024.