Email Bounces

What is an email bounce? 

An email bounce signifies non-delivery of your email message. When this happens, the mailer will receive an automatic notification of the delivery failure. This failure originates from the recipient’s mail server for a number of reasons (explained below).

Soft Bounce vs. Hard Bounce

There are two types of bounces that you can receive – a soft bounce/block or a hard bounce. Think of soft bounces as blocks that are a short-term issue–you don’t need to permanently take these addresses off of your list. However, hard bounces are either invalid or non-existent addresses that should be removed immediately.

Soft bounce

A soft bounce means that the email address was valid and the email message reached the recipient’s mail server. However, common reasons it bounced back include:

  • The mailbox was full (the user is over their quota)
  • The server was down
  • The message was too large for the recipient’s inbox

We continue to attempt to send these messages for up to 72 hours until the message is delivered. If a message is continuously deferred for 72 hours, we will stop trying the resend for that particular email, but they will be eligible to receive other sends in the future.

Hard bounce

A hard bounce occurs when the message has been permanently rejected either because:

  • The email address is invalid
  • The email addresses does not exist

We add these hard bounced addresses to a suppression list and they will be excluded from future sends.