Basic services such as email, databases, API platforms and a host of other services are now getting packaged into public cloud services. But the indie providers are still showing strength through integrations with infrastructure and platform-as-a-service offerings. The email transaction market category is an example of how cloud services providers and independent vendors are finding their own ways to differentiate from each other.

SparkPost is a recent add-on in the Heroku marketplace where it’s offering developers up to 10,000 emails a month for free. The news points to the continued need for email integrations that developers can build into their apps. Before looking at some of the providers out there, let’s take a step back and get a look at email use, and its impact on the overall market landscape.

During the first quarter of this year, two-thirds (67 percent) of all email opened in the United States occurred on a mobile device, according to email marketing vendor Movable Ink.

Although Apple devices hold the crown for the highest email open rates, according to a SendGrid survey, Android- and Linux-based devices are the two fastest-growing segments for email opens in the United States, growing 71.4 percent in the past year.

Aside from marketing and newsletters, approximately 60 billion transactional emails are sent each month – alerts to password resets, sign-up confirmations and purchase shipping notifications.

Transactional email differs from marketing and newsletters in that it has to interact with an application, requiring developers to be involved with that integration, but also to ensure it works properly on multiple devices. And more email integrations are coming all the time, such as the Uber Ride Reminder add-in for Outlook and the ability to send money online through the PayPal add-in.

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That means keeping developers happy. That’s just as important for the major cloud services as it is for the independents. Here are some email delivery providers that are findng their way in the growingly intertwined cloud services arena.

Amazon SES

Amazon SES, or “simple email service,” is a barebones offering that comes with a barebones price.

It’s an outbound-only service for sending emails via its API or SMTP server. You track bounced emails using Amazon’s SNS notifications system, set up DKIM (DomainKeys Identified Mail) records with Route 53, and store files with S3.

It does not offer click tracking, open tracking, incoming email support or custom pricing for big senders as a core part of its service – and with so many vendors offering similar services, many are banking on extra features to draw customers.

Price: Free for sending up to 62,000 emails a month via EC2 or through AWS Elastic Beanstalk; above that $0.10 per thousand emails sent.


SendGrid offers a transactional email service and an email marketing platform all in one.

It uses APIs for sending emails, an event API to get notifications and stats about your emails automatically, and a parse API to grab the contents of replies for use within your app.

It provides custom email authentication certificates; integration with ISP feedback loops to know when your messages are marked as spam; IP address reputation scoring to determine the likelihood that your messages will be marked as spam; detailed analytics and reports; and the option to download the data and look through it on your own.

Integration partners include Windows Azure, HP Cloud, Softlayer, Rackspace, Heroku, Engine Yard and CloudBees; and customers include Airbnb, Pandora, HubSpot, Spotify and Uber.

However, it was the target of a breach in April, and has been working to expedite the release of API keys, IP whitelisting, and enhanced two-factor authentication.

It announced new white-label management features in July as well as a customer portal with new UX and UI; revamped web API that standardizes return data patterns, response codes, and endpoint names; Advanced Suppression Manager (ASM), which allows recipients to manage their email preferences.

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Price: $9.95 for up to 40,000 emails a month, up to the Platinum level of $399.95 for 700,000-plus, and custom pricing above that.


Mandrill was built by the MailChimp marketing email pros, with its entire SMTP relay infrastructure built atop AWS.

Mandrill provides dedicated IP addresses, in-depth analytics, template hosting, inbound email parsing, and more. There’s also a split-testing tool that allows you to try out and test so you can use different templates; custom SPF (Sender Policy Framework), DKIM, and tracking domain on all plans; a dashboard of detailed stats and searchable logs of your past 30 days’ worth of emails sent as well as tags and metadata you define.

You can test your email templates against spam filters in Mandrill to achieve the highest delivery rates.

However, it too was the target of a breach in March.

Price: $9.95 for up to 25,000 emails a month; $0.20/thousand for the next 1 million; $0.15/thousand for the next 5 million; $0.10/thousand for anything beyond that.


Mailgun is designed for big senders. Rackspace bought the startup, which billed itself as “Twilio for email,” in 2012.

It offers isolated sub-accounts for each domain you add, 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.

You can send up to a thousand personalized email messages with a single API call, use tags to segment your email lists, and run A/B tests. And Mailgun can push a webhook to your app to notify you when an email is delivered, opened, or anything else you specify.

It allows you to handle each of your company’s projects or client accounts separately, or if you don’t want to handle it yourself, it also offers a managed service.

It integrates with Heroku, Engine Yard, and AppFog. Customers include GitHub, Stripe, 37 Signals, and PagerDuty.

Price: The price is per email and it’s free for the first 10,000 emails; add on $0.00050/email for the next 500,000 ($250 for 510,000 emails); plus $0.00035/email for the next 1 million ($600 for 1.51 million emails); $0.00015 for the next 5 million ($1,350 for 6.51 million emails); and $0.00010/email for any additional ($1,699.00 for 10 million emails).

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SparkPost boasts the highest deliverability of any email provider — delivery rates of 97 to 98 percent with customers including Pinterest, Zillow, LinkedIn and Twitter. The company also recently announced it supports sending email on Apple Watch.

SparkPost’s SMTP and REST APIs allows developers to use email in their web or mobile apps, regardless of language. The integration with Heroku simplifies the sign-up and installation process, allowing users to get started with comprehensive email APIs and pre-built SDK libraries, as well as access email analytics in real time with webhooks. It also provides access to support documentation, how to collect insights within Heroku on SparkPost app usage, and best practices for establishing simple navigation between platforms.

Its Adaptive Email Network automatically tailors messages through the SMTP protocol to address bounce codes for all the various ISPs to comply with their rules and ensure higher delivery rates, according to the company.

Price: Free for 10,000 emails a month, up to $574.95 for up to 1 million/month; and custom pricing above that.


Postmark is specifically focused on transactional email. It boasts it lets you see who opened your email, where they opened it, what clients and platforms they used, and even how long they spent reading it.

It offers an API with code snippets and libraries for popular languages and platforms for easy integration into a website or app; 45 days of searchable history; inbound parsing with messages converted to JSON that can be searched and retrieved directly in the app or API.

Instead of having to subscribe to a plan with a certain level of use, it sells email credits that can be used as needed.

Price: Trying out their service gets you 25,000 credits for free; otherwise it’s $1.50/thousand for 1,000 credits; $1.00/thousand for 500,000+ credits; up to $0.50/thousand for 2 million+ credits.

Feature image: “Fair Time” by GollyGforce – Living My Worst Nightmare is licensed under CC BY 2.0.