Internet Performance Delivered right to your inbox

Cloud Email Delivery vs. Open Source: What’s The Difference?

It’s not everyday that the subject of email delivery makes it into the news so when it does, the Dyn email team sure gets excited.

A recent post about Postal, an open source email delivery platform, made it to the top of Hacker News and we couldn’t help but notice a few key items with its documentation, and the comment trail on the post. These items indicated a real advancement in the general industry’s understanding of the best practices for email delivery.

What is Postal?

Postal provides an open source framework to create an email delivery service on your own infrastructure. They have done a good job offering a robust feature set for email delivery with both SMTP and API endpoints, and flexible configuration options. These features are similar to what’s also offered on Dyn Email Delivery, so what’s the difference between an open source platform and a cloud provider?

Top 3 differences: Postal vs Cloud Email Delivery

1. Deliverability remediation is up to you

Cloud email delivery services proactively manage their platform’s reputation and deliverability through established processes for configuration and maintenance, as well as reactive maintenance when necessary.

As noted throughout the post, deliverability management is a complex area of study. Spam has evolved over the years and so has the methodology of keeping it out of users’ inboxes. This leads to a complex set of systems that differs at each mailbox provider, and only so much of that experience can be coded into an open source project like Postal. Some of the key differences center around the configuration of your domain, DNS, and infrastructure which you’ll need to do yourself with an open source project, but comes out of the box with a cloud provider.

2. Customization per mailbox provider

Email delivery is far from an ideal world. Common mailbox providers publish configuration settings on how they prefer mail to be delivered to them which results in customized SMTP settings on how many connections per IP that can be opened, how many messages per connection, and what certain SMTP response codes might mean to them.

Cloud services like Dyn Email Delivery have had years to perfect these SMTP settings at mailbox providers across the globe. Even if you’re not sending to a certain domain (mailbox provider) yet, you might in the future and the experience from a large email delivery vendor will help ensure your mail gets delivered.

In addition to SMTP settings and codes, bounce codes can vary drastically. Ensuring your system is classifying these codes correctly may help ensure you do (or don’t) continue to email addresses when appropriate. This will help ensure you keep as much business as possible without impacting deliverability and inbox placement rates in the future.

3. Scaling and redundancy is up to you

With cloud services, the providers take a lot of the grunt work on scaling resources, providing elastic, load balanced, and redundancy options automatically for you. Services like Dyn often have a very scalable model from a start-up to the biggest of enterprises to allow for varying usage volumes. You’ll never need to worry about what compute shape or database size you have provisioned as that’s already taken care of.


Postal has done a fantastic job incorporating key features and functionality of an email delivery solution, but as detailed above, there are some critical areas of difference between an open source email delivery solution and a cloud email delivery vendor.

Share Now

Whois: Mike Veilleux

Mike Veilleux is a Director of Product Management at Oracle Dyn Global Business Unit, a pioneer in managed DNS and a leader in cloud-based infrastructure that connects users with digital content and experiences across a global internet.