Speed and redundancy for SMTP with Postfix

Transactional email needs speed. Users generally don't want to wait for their password reset information or a confirmation that their order went through, and although there are a lot of factors that can influence delivery speed, most of us expect that an email comes within a few minutes of requesting a password reset or completing an order on our favorite website. On the Mandrill side, we're doing things like adding SMTP servers around the world to speed things up for our users. Using a local Postfix server is one step you can take to help increase speed and redundancy for your emails.


Postfix is a commonly-used mail transfer agent(MTA). If your server is configured to accept or send email, you may already be using Postfix to handle the email delivery. It's installed by default for sending mail locally for many Mac OSX computers and in Linux distributions. Configuring Postfix to relay through Mandrill only requires a few changes to your Postfix configuration.

Why use Postfix with Mandrill?

You could use any number of SMTP libraries in your application code to send email, or leverage the power of the Mandrill API. Here's why we think Postfix is a tool for your email arsenal:

  1. If you're already sending email through Postfix, a few configuration changes help you add advanced tracking and analytics to your emails, along with the proven delivery infrastructure for Mandrill and MailChimp. All without making changes to your application code.

  2. If you're not in close proximity to one of Mandrill's distributed SMTP servers, or if you want to reduce latency for your application, having your app relay to a local Postfix server can save a lot of overhead in transferring the mail from your app.

  3. Postfix automatically queues and retries emails, so if your server experiences connection issues, you don't have to build retry logic or queuing since Postfix will handle it automatically.

  4. Postfix supports pipelining, which isn't supported for many SMTP libraries. Pipelining is a way to reduce the chattiness of SMTP and using pipelining can significantly speed up delivery of your email to Mandrill's servers for processing.

Whether you're already using Postfix or not, there are compelling reasons to use Postfix to speed up and add automatic queueing and retries for your email. More advanced Postfix configuration options make it possible to have complex logic about what emails are relayed through which servers, giving you fine-grained control over your email sending.