The 9 Best Transactional Email Services to Send Thousands of Emails

Ever stopped to think about what happens to your email message after you press "Send"? If you're sending personal emails through an email app, your emails likely get routed through Gmail or another email service's Simple Mail Transfer Protocol (SMTP) service to your email recipient's email service's SMTP service. Even if you email hundreds of people with an email newsletter app, you click send and the messages quietly get delivered. It just works, and so most of us ignore it.

But if you're sending thousands of emails a day through your app, or are delivering your company's newsletter to millions of people, suddenly you need to think a lot more about how your emails get sent. You'll very likely need a transactional email service, a dedicated email sending service that'll make sure your emails get delivered no matter how many you need to send.

Ready to send emails? Jump ahead to our roundup of the best transactional email services. Or continue reading to learn why you need a transactional email service, what they offer, and how to use one.

Originally published January 20, 2015; updated most recently June 28, 2018.

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What is Transactional Email?

"Transactional email: Services to send bulk email messages via an API or SMTP server."- AUTHOR

Sending an email—even a handful of them at the same time—isn't difficult. Your standard Gmail account will let you send up to 500 emails per day, while hosted Exchange accounts will let you send up to 30 messages per minute. An email newsletter tool or drip email app is the next step up, to send thousands of marketing emails a week. It's when you need to send thousands or millions of emails a day that you need another solution.

Perhaps you have your own app, and you want to send emails through it. Maybe you like to self-host all of your business tools, or you'd rather be able do more with your emails than what a standard email app will let you. Or perhaps you've hit your email newsletter's top plan. That's when you should consider a transactional email sending service.

"Don’t reinvent the wheel. The internet is full of wheels… and most of them have APIs."- Andy Chung, Entrepreneur

Today, there's a service for everything. You can run your application on Heroku, accept payments with Stripe, call phones and send SMS messages via Twilio, and add just about any other feature to your app with any number of other services. These "feature-as-a-service providers", as entrepreneur Andy Chung calls them, give you the pieces you can use to build your app in less time. Instead of working out payment deals with banks and figuring out how to code a working internet phone system, you spend your time making your app and let other teams focus on those problems.

Email's the same. Transactional email services—including Amazon SES, Mandrill, Mailgun, Postmark and more—let you send email messages via an API or SMTP server. Instead of building your own system to send email messages, you can add a few lines of code to let them send emails for you, then never worry about email again.

You could run your own email server. There's an email server built into your Mac and most versions of Linux, and plenty of other email servers like Exchange you can run for free or license. It might look cheaper at first, but running your own email service—just like running your own payment service—is likely not your best strategy.

Here are the three best reasons why you should outsource your emails and use a transactional email service:

1. Send More Messages, Faster

Gmail's limit of 500 emails a day might be the first reason you'd look for another way to send emails, but you might face similar limits with your own email server. Many shared hosting services will limit how many emails you can send per day, as detailed in this list by MailPoet, so you'll soon have the same problem you would with Gmail or Exchange.

Even on your own private server, sending thousands of emails at once can be a technical challenge you're not ready for—or simply more trouble than it's worth. That's why you'll find logos of popular companies of all sizes on transactional email sending services' sites: it's easier and often more efficient to use a service that's solely focused on sending emails well. As Tom Cook, former Quora employee said about Quora, "they use (Sendgrid) because setting up mail delivery infrastructure is a real headache at their size."

If you're running your own email infrastructure, sending out double or triple your standard number of emails might mean you need a new server or significant developer time. With an email sending service, on the other hand, it'll at most take a few changes to your integration as the KnackForge team found. A few tweaks to Mandrill's Drupal integration later, and they were able to send 75,000 emails an hour.

Maybe you need to send 7 emails a minute, or 7 million a month. Either way, the email service will be ready for your load, with little to no work on your end.

2. Ensure Your Messages Get Delivered

"Sending emails from your app can suck. Half the time, messages that get sent from your own server just get dumped into the recipient’s junk folder."- Cory LaViska, Surreal CMS developer

Even if you're running your own servers, and have the infrastructure to send the messages you need, there's another catch with running your own email sending server: deliverability. You might technically be able to send emails on your own, but the chances of those emails showing up in your recipients' inboxes are slim to zero.

Most email apps today strictly scan emails to eliminate spam, and one of the many things they use to weed out spam messages is the IP address that's used to send the emails. They check against both blacklists—IP addresses known to send spam—as well as whitelists—IP addresses know to be good in general. If you're sending emails from a shared server, there's a possibility your IP address is already on those blacklists.

If you have your own IP address, your mail still may get marked as spam if you're not on a whitelist. As the Koomohost team related, "If your site is not associated with a reputable or identifiable IP address and domain name, most email providers will mark it spam or not accept delivery." You'll also need an SPF or DMIK record, email validation tools that may be difficult to implement on your own but are included with most email sending services.

You could test your server first to see if your emails get marked as spam, but your test emails to your own address just might come through with the problems only showing up once you're sending thousands of emails. Or, if your company's the size of Google, it might make sense to get your own IP whitelisted. For everything in between, an email sending service makes the most sense.

"Leveraging email deliverability tools seems like an unnecessary upfront cost and waste of time (especially if you are small or just growing your lists), but ironically this is when you need these services the most," explains entrepreneur Jeremy Vandehey. There's no point in sending emails that don't get delivered, and there's no point risking it when you're just starting out and every email really counts.

3. Do More With Your Emails

Add deliverability onto the trouble of running yet another service—one you're likely inexperienced at managing—and email sending services start looking far better. But there's also another reason to pick them: the extra features they offer.

Some transactional email services, such as Amazon SES, are barebones and focused only on sending emails—and priced accordingly. But most others include advanced stats, notifications, filtering and more that let you do far more with your emails. With a bit of coding, or just some clicking around in stats dashboards, you can accomplish amazing things.

Karl Seguin, for instance, put Postmark to work not just in sending emails, but also to make it easier for customers to signup. That's something that would have been difficult or impossible to do with a self-hosted email service—and the ironic thing is, Seguin wasn't initially convinced of the benefits of a transactional email service.

"Why would you outsource and pay for something as basic as sending out email?" wrote Seguin. But then it clicked. Not only did Postmark help them send emails easier, its bounce API helped them automatically update users' profiles with their valid email address without having to click an activation link. "The end result is that our website flow is friendlier. Users can start using the site right away and our welcome email is just a welcome email—no special activation instructions, no huge deal if it get marked as spam."

Once you have users and are sending them emails, the stats and insights you can get from them can be invaluable. Nathaniel Eliason, Zapier's marketing intern this year, used Mailgun and its stats when building his own startup. With some custom coding, it enabled them to see if people didn't accept their email invite within a week, or if they signed up then bounced, and more. Email services give you the ability to customize your email flow, keep people coming back, and more, without having to code detailed email analytics on your own.

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The Best Transactional Email Services

Picking a service to send emails is similar to picking between different cell service providers. They each offer a very similar service and pricing. The difference is in the small things: the libraries and integrations that make them easier to use with your app, stats and dashboards that help you hone your emails, and more. Here are the best to pick from—and what makes them unique:

• Amazon SES to send emails cost effectively from a barebones platform
• SendGrid to send transactional emails and marketing campaigns together
• Mandrill by MailChimp to send transactional emails with your newsletter subscriber details
• Mailgun to ensure you're sending messages to valid email addresses
• Mailjet to build transactional emails templates with a drag-and-drop editor
• SendinBlue to send transactional email, newsletters, and SMS messages together
• Postmark to send transactional emails fast with detailed stats
• Campaign Monitor Transactional to use the same templates for newsletters and transactional emails
• SparkPost to see how your emails perform with 40 metrics

Amazon SES

To send emails cost effectively from a barebones platform

Amazon started as the world's largest bookstore, but today they're also one of the world's largest web services company. Best known for S3—file storage in the cloud—and EC2—their servers-in-the-cloud—Amazon also offers CDN services, online databases, DNS server and more. Among the offerings is Amazon SES, or "simple email service", a transactional email service that's also one of the cheapest and most barebones offerings available.

Amazon SES is designed to work with Amazon's other hosted services. Rather than supporting everything in one place, you'll use SES solely to send emails via its API or SMTP server. Then, you can track bounced emails with Amazon's SNS notifications system, setup DKIM records with Route 53, and store files with S3. It doesn't include analytics tools, but you will find stats on your successful deliveries, bounced or rejected messages, and complaints.

It's only an email sending service, and if you already use Amazon's other email services or are fine filling in the gaps with other tools, then it's a simple and cheap way to send bulk emails.

Amazon SES Pricing

Check Amazon SES Status: https://status.aws.amazon.com (includes uptime for all Amazon cloud services)

For more info on features and pricing, see our Amazon SES review.

See Amazon SES integrations on Zapier.

SendGrid

To send transactional emails and marketing campaigns together

One of the largest transactional email sending services, SendGrid delivers over 40 billion emails each month for companies like Spotify and Uber. It's designed to be simple to integrate into your app, with a number of different APIs and supported client libraries. You'll find built-in support for email authentication and reputation scoring for your IP address to make sure you emails get through, along with a library of online documentation and videos to help guide you along.

In addition to sending standard transactional emails over its API, SendGrid also includes a marketing platform with a drag-and-drop email template editor and online list management. You can create templates and manage your lists in SendGrid, then use that data through SendGrid's interface or its API—or you can handle everything yourself in your custom apps. And, if anyone replies to your emails, SendGrid can parse those emails and any attachments they may contain, and send them along through webhooks or APIs.

SendGrid Pricing

Check Sendgrid Status: http://status.sendgrid.com

For more info on features and pricing, see our Sendgrid review.

See Sendgrid integrations on Zapier.

Mandrill by MailChimp

To send transactional emails with your newsletter subscriber details

The company that makes MailChimp doesn't only send beautiful email newsletters; you can also use its email sending expertise to ensure your app's emails get delivered. That's what MailChimp add-on Mandrill is designed for.

Originally a project to integrate MailChimp with Amazon SES, Mandrill became a standalone project to add extra features they couldn't offer with Amazon SES as an add-on to MailChimp. As such, Mandrill is a tool for sending emails to your customers automatically, with better template design combined with your MailChimp mailing lists. You can share your contact data from your email newsletters to your transactional messages to make better notification emails from your app with the contact detail your marketing team maintains in MailChimp.

Mandrill by MailChimp Pricing

Note: MailChimp Transactional is a Mailchimp add-on, and requires a paid MailChimp account starting at $10/month for 500 subscribers. See our MailChimp Review for more info.

Check Mandrill Status: http://status.mandrillapp.com/ (includes uptime and deliverability stats)

For more info on features and pricing, see our Mandrill review.

See Mandrill integrations on Zapier.

Mailgun

To ensure you're sending messages to valid email addresses

Mailgun is designed to be a reliable email service for developers. Not only can it deliver your emails well, it also includes email validation features to check and make sure you're sending emails to valid addresses and don't waste money trying to send emails that bounce.

You can send emails with isolated sub-accounts for each domain you add, giving you an easy way to manage all of your email lists separately or manage client emails along with your own. It includes batch sending features to personalize emails, detailed analytics and logs, and a powerful parsing engine to turn incoming emails into JSON and route it where you want.

All transactional services will help you not have to worry too much about email, but there are still things you'll want to think about: your delivery rates, email reputation, and more. If you'd rather let someone else take care of those, too, Mailgun also has a managed service that can take care of the rest of your email solution. That way, you can focus on your code and never worry about email, even if you're sending millions of messages a month.

Mailgun Pricing

Check Mailgun Status: http://status.mailgun.com

For more info on features and pricing, see our Mailgun review.

See Mailgun integrations on Zapier.

Mailjet

To build transactional emails templates with a drag-and-drop editor

Picking a transactional email service doesn't have to mean you leave behind the features other email marketing apps offer. Mailjet brings the best of both worlds to the table, as a full-featured email marketing and transactional email sending service.

You can customize Mailjet's email templates with a drag-and-drop editor, store your customer's data and use it to personalize your emails, then use that data to segment your lists and send the perfect emails to your audience. Or, you can do the heavy lifting on your own, and only send emails using Mailjet's API.

Either way, you can test your campaigns and improve them using Mailjet's A/X testing, which lets you test up to 10 variations of your campaign and then send the best version to the remainder of your recipients. There's also real-time analytics and data on your emails, and tools to compare each set of messages to your last, to see how your marketing is going over time. It keeps all your email work together in one place.

Mailjet Pricing

Basic plans include core email sending features; Premium plans include segmentation, A/B testing, marketing automation, and more.

Check Mailjet Status: https://mailjet.statuspage.io

For more info on features and pricing, see our Mailjet review.

See Mailjet integrations on Zapier.

SendinBlue

To send transactional email, newsletters, and SMS messages together

Want to send transactional SMS messages along with your transactional emails? SendinBlue might be the email service for you. It's another app that includes email marketing along with a transactional email API, and also includes SMS marketing to give you one more way to get in touch with your audience.

Using the same REST API, you can create campaigns using SendinBlue's marketing platform, or you can send transactional email and SMS messages. You'll be able to keep up with all of your customer's data with SendinBlue's integrations with eCommerce and CMS platforms, and can trigger campaigns from your app. Say you send a receipt from your app with SendinBlue's transactional service, and your customer clicks the link. SendinBlue can log that interaction and automatically send a followup drip email on its own. It combines all of your marketing to help tie your email tools together.

SendinBlue Pricing

Check SendinBlue Status: https://apidocs.sendinblue.com/api-status/

For more info on features and pricing, see our SendinBlue review.

See SendinBlue integrations on Zapier.

Postmark

To send transactional emails fast and detailed stats

Postmark goes back to basics, focused on core email sending more like Amazon SES. Only here, you get more features that help you improve your emails. It's fast—aiming to deliver emails within 10 seconds after you send them.

That comes with 45 days of searchable history, so you can see the full contents of the emails you've sent and pinpoint why they bounced. You can also see full profiles of each of your email recipients, complete with info about which emails they open, their location, and more. It pulls your stats into an easy-to-read sentence about how your emails are performing. And it can even store your email templates so your app only has to send the message content, and it'll merge them with templates and send them automatically.

Postmark Pricing

Check Postmark Status: https://status.postmarkapp.com

For more info on features and pricing, see our Postmark review.

See Postmark integrations on Zapier.

CampaignMonitor

Campaign Monitor Transactional

To use the same templates for newsletters and transactional emails

Transactional emails are supposed to be geeky—and usually they are. You'll interact with them through an API, design your emails in HTML, and rarely open the email sending app itself. Campaign Monitor, is the opposite. It's first and foremost a design-centric email tool for sending marketing and drip emails, but it also includes a transactional email service. You can use the same templates you're already using for marketing emails for the signup, receipt, shipment, and other transactional emails you send.

If you're already using Campaign Monitor to send marketing emails, your same account and email quotas can be used to also send transactional emails. You won't need a new account or a new plan—all you'll have to do is configure your app's SMTP server or add API calls to send transactional messages, and you'll have all your communications going out from the same account. It's built around subscribers, making it cost-effective if you send a lot of messages to the same contacts who receive your email newsletters.

Campaign Monitor Pricing

Alternately, you can pay $5 per campaign plus 1¢ per email for occasional large campaigns

Check Campaign Monitor Status: https://status.campaignmonitor.com

For more info on features and pricing, see our Campaign Monitor review.

See Campaign Monitor integrations on Zapier.

SparkPost

To see how your emails perform with 40 metrics

Sending transactional emails shouldn't mean you have to do everything with your emails aside from sending them. SparkPost makes it easy to send customized messages, with HTML templates that support variables. You can even add nested, conditional rules, to only substitute data in the template for specific circumstances, for an easy way to send emails that are personalized specifically for each reader.

You'll then be able to quickly see how your emails are performing, with SparkPost's dashboard's custom views that let you drill into 40 metrics to see specifically where your emails are doing best—and how to improve the others. And you'll be certain your emails are being sent securely, since each API key can be restricted to specific IP addresses and have its own permissions for a secure email sending setup.

SparkPost Pricing

Check SparkPost Status: https://statusgator.com/services/sparkpost

For more info on features and pricing, see our SparkPost review.

See SparkPost integrations on Zapier.

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How to Use Your Transactional Email Service

Now that you're convinced not to run your own email server, and have picked out a service to send your messages, it's time to actually start using it to send emails. Unlike most apps, you can't just fire up your new email sending service, click three buttons and send out a bulk email. You'll instead need to integrate them with your apps and tools, or fire up terminal to send messages manually.

Here's some of the many ways you can put your transactional email service to work today.

Send Emails From Your Software

Whether you have fancy online apps that want to send emails, or are still using traditional desktop software, many programs will let you configure your SMTP server to send emails. There's no need to put in your Gmail credentials anymore. Instead, put your transactional email service's SMTP server info into your app's settings page.

Then use your app as normal, and it'll send emails using your transactional email service—complete with your default template if you're using a service that adds a template to your messages. That's how the Digital Fusion team sends emails from their Filemaker database. They've integrated Filemaker with Mandrill's SMTP server so they can get all the advantages of an email sending service from a traditional app.

"Even if you wish to use (Mandrill) just via SMTP alone it makes sense," says Digital Fusion developer Daniel Wood. "The Mandrill SMTP credentials are reliable, secure, and work anywhere (subject to firewall restrictions of course). In addition, you get all the benefits of comprehensive email tracking and settings to help customize the experience."

Add it to Your Site and App's Code

Have an app that can send emails? The best way to use a transactional service is to integrate it with your app. You'll find code snippets for most transactional services to integrate them with your app using PHP, Python, C# and more. Typically, it'll just take a couple lines of code to get their API working with your code base, so just look at the documentation for each service before you dive in.

Beyond that, there are modules, plugins, and libraries to integrate many of the popular email sending services with apps that you're likely already using. You can find WordPress extensions and Drupal modules that'll let you send emails with the service of your choice, and more. Look around and see what's available for your tech stack, and that might be one of the things that helps you decide which service to use.

Get New Apps for Email Sending Services

If you'd like the features and performance of a transactional email service but don't want to code, you need an app designed to work with transactional services. They handle the code needed to create your emails and make them look nice, and use the service of your choice to send the emails out, giving you the best of both worlds.

SendWithUs, one of the apps included in our roundup of best email newsletter apps, is one such tool. It helps you create beautiful templates for your emails, with analytics, A/B testing, customer profiles, segmentation, and automatic drip campaigns. All you'll have to do is add SendWithUs' API to your site to send emails or add new contacts.

For a simpler experience, Sendy is a self-hosted email newsletter app that sends messages via Amazon SES. You'll just install your copy of the app, add your SES account info, then create and send apps without ever having to touch a line of code. Or, EmailOctopus gives you similar features in a hosted app. They're some of the simplest ways to send emails with a transactional email service.

Automate Email With Zapier

Even if you can't code, you can still make your own apps and integrate your email service with any other program using app automation platform Zapier. Connect your transactional email service to Zapier, then you can send emails automatically from any of your other apps.

Check out our Transactional Email Integrations for inspiration.

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Sending bulk emails—directly from your app, with a bit of code in terminal, or through any app that lets you send emails—doesn't have to be difficult. With a transactional email service, you can send all the emails you need from the apps you're already using. You might even be able to do more with them than you've ever done with your emails before.

And if you're only sending several thousand emails a month, transactional email services are the best way to send them for free.

Next

Whether you're sending emails from a drip or newsletter app, or are using one of these transactional services to send your messages out to the world, you'll want to make sure your emails are as effective as possible. For that, you'll want to A/B test your messages, crafting separate versions of your messages and automatically testing to see which version performs best. We'll learn all about how to A/B test emails in the apps you're already using in the next chapter.

Go to Chapter 10!