Hard & Soft Bounces
A bounce occurs when we try to send an email to a recipient but it is rejected for delivery by the recipient's mail server (e.g. Yahoo, Gmail or AOL).
The reason a bounce can occur ranges from technical problems with the recipient mail server to non-existent email addresses.
Email that cannot be delivered is classified as either a hard or a soft bounce and there are sub-classifications within each of those responses that provides further information in relation to the reason for non-delivery.
Mail server Spam / Junk filters can also generate hard and soft bounced responses as emails are rejected for content or sender reputation related reasons.
Hard Bounces
The message has been permanently rejected; it is highly unlikely to ever be accepted for delivery. Common reasons for Hard Bounces include: "Bad Mailbox" - the email address does not exist and "Bad Domain" - the domain does not exist or is unreachable.
Soft Bounces
The message has been temporarily rejected. Common reasons for a soft bounce include: "Spam Related" - the message is believed to be unsolicited and "Quota Issues" - the recipient mail server is throttling the number of emails allowed through.
Common Questions
How does this relate to the "Auto-cleansed" metric?
All bounced messages are passed through the system Auto-cleansing facility: any bounced messages that indicate a delivery failure that is unlikely to recover (e.g. Bad Mailbox) has the related User opted-out from all future communications.
The number of opt-out actions made by the Auto-cleanser for a particular Email Campaign will be displayed as the "Auto-cleansed" metric.
There are a variety of rules used by the Auto-cleanser to determine when a User should be opted out, see Auto-cleansing Rules for more information.
Do I need to do anything with my Hard or Soft Bounces?
If an Email Campaign has a high percentage of bounces it could indicate an underlying issue (anything over 2-3% is usually cause for concern). Under these conditions it is highly recommended that you check the Deliverability page of the Campaign Report or download the details of the Hard and/or Soft Bounce metrics for further analysis.
When viewing the contents of the bounce report look for the most commonly occurring type of bounce category as these will likely give an indication of the cause.