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How GoSquared processes email bounces

Last updated: 1st August, 2022

How does GoSquared Engage classify email bounces?

When you send email messages from our Engage platform, some emails to certain users may ‘bounce’.

This can happen for a variety of reasons, and depending on the reason, GoSquared will classify and process the bounce differently.

GoSquared categorises bounces according to the “bounce reason” — this is a response code that we receive for every email sent out.

Depending on whether it’s a soft or transient or hard bounce, GoSquared will block sending to the email address for a variable period of time:

  • Transient bounces (e.g. you sent a message that is too large, but the mailbox is likely fine) get no timeout at all.
  • Soft bounces (e.g. mailbox full) get a 1-hour timeout.
  • Hard bounces (nonexistent recipient, permanently banned) get a 7 day timeout.

You will be able to identify if any users’ emails have bounced for any of the reasons above, by clicking the Bounced list within your message’s click-tracking.

For a more technical explanation, we send out emails from our email-sending provider, SparkPost.

If a SparkPost email receives a 4xx rejection from the ISP, SparkPost will log a “delay” event.

SparkPost’s retry algorithm will re-attempt delivery for each message a certain number of times over a time period. For example, a message could be retried up to 6 times during a 72 hour time-period. The message will not appear in GoSquared as a bounce at this stage.

If the message is successfully delivered upon a retry, this will be logged in GoSquared under the message’s Received list.

If SparkPost exhausts the maximum number of retries (or maximum time period the message is eligible for delivery) and the remote server has not accepted the email, Sparkpost log the message as “bounced”. At this stage the message will be logged in GoSquared in your Bounced list.

The type of bounce recorded will depend on the final 4xx response string from the ISP. This category is not typically classified as a ‘hard’ bounce.

If SparkPost receives a 5xx response from the ISP, it will log a “bounce” event and classify the bounce based on the 5xx response string. 5xx responses are known as “Permanent Failures”.

For more information on SparkPost’s definitions and process of recording bounces, please read their article here.