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Managing different types of email

Each type of email has unique time constraints. For example: an email containing an activation link should arrive in a few seconds, whereas for a newsletter, the delay does not necessarily have to be so short.

With Mailjet, senders can manage the different types of email by defining up to four priority levels. This simplifies the process and opens up a host of possibilities. But nevertheless, it is a tool that should be handled with care.

What priority management allows you to do

Let’s imagine that you need to manage four types of email:

  • Type A- Emails related to service monitoring (ex. a message notifying users that your site is down)
  • Type B-The flow of transactional emails from your site/application
  • Type C-The flow of marketing emails related to your clients '/users' lifecycles
  • Type D- The flow of a flash sale campaign

The “Type A” emails should always arrive instantly and go before the others, including transactional emails: this queue is reserved for absolute emergencies. This is a tool to keep in case of big emergencies (ex. service outage). The transactional emails, “Type B,” should always remain "high priority".

On the other hand, in the case of a flash sale, you want to inform the maximum number of people as quickly as possible. The goal is to quickly activate a maximum amount of transactions and to create a sense of scarcity. You may therefore want to transmit the “Type D” emails before “Type C.” This subtlety is simple to implement: you can do it by indicating the priority level in the header of your emails.

How to use the priority tag in your headers

There are two queues: “high priority” and “low priority.” Priority values are included in the headers. Just use the following tags (case sensitive): “X-Mailjet-Prio:N”, where N may be equal to:

Low priority queue

  • 0 → Low priority queue (FIFO)
  • 1 → Goes before the low priority queue (LIFO)

High priority queue

  • 2 → High priority queue (FIFO)
  • 3 → Goes before the high priority queue (LIFO)

Careful, note that:

  • By default, transactional emails should be sent with code 2 and marketing emails with code 0.
  • Moreover, by default, emails sent using the Newsletter tool are classified as 0, and those sent via our SMTP are 2.
  • Codes 1 and 3 should not be used except for very precise purposes: the example situations above or any scenario in which tight control of email flow is necessary.
  • Whether high or low priority, the processing speed is the same: it is only the order of priority that changes.
  • Code 3 can block emails with code 2; it is not advised to use it for large volumes and is intended more for “monitoring” emails in critical situations.