Help Articles

Bounces: Soft Bounce vs Hard Bounce


One of the advantages of using an email marketing service like ActiveCampaign is it’s ability to provide valuable reporting to you.   With your account, you can track opens, forwards, clicks, etc.  This positive interaction data allows you to see the effectiveness of your campaigns.

It is also important to know the “negatives” of your campaigns: unsubscribes, bounces, complaints.   ActiveCampaign tracks these for you.    Knowing your “negative” rates allow you to know more about the quality of your list.  It exposes flaws that you may have with regards to your processes.

One particular metric that you should be concerned about is Bounces.    The rate of your bounces gives you an indication of the quality of your list.    Having high bounces can mean you may have an old list, your subscription process is flawed, etc.

It is thus important to understand what bounces are and what types there are.

What is a Bounce?

A bounce is basically a rejected email.   When you send your campaign, ActiveCampaign attempts to send it to the recipient.   When the email gets to the receiving server (where your subscriber’s email is located), the receiving mail server either accepts the email or rejects it.    The rejection is called a Bounce.

There are 2 types of bounces: Soft and Hard.

Soft Bounce

A soft bounce normally happens when the receiving Mail Server is temporarily unable to receive the email.  There are several reasons why this would happen.   The following are reasons for soft bounces.

  • A server is unavailable or it’s down
  • The server is overloaded
  • The recipient’s mailbox is full
  • Your message size is too big

Soft bounces would normally resolve itself.   ActiveCampaign would try 3 times to send your campaign.   If the email address soft bounces 3 times, it would be considered as a hard bounce.

Hard Bounce

A hard bounce is more permanent.   In terms of ActiveCampaign, 1 hard bounce removes the subscriber from the list.

There are several reasons why an email would hard bounce.    The main characteristic though, is that it is a permanent rejection.   Below is a list of bounce codes that we use and support.

Bounce code

Bounce type


5.0.0 Hard Address does not exist
5.1.0 Hard Other address status
5.1.1 Hard Bad destination mailbox address
5.1.2 Hard Bad destination system address
5.1.3 Hard Bad destination mailbox address syntax
5.1.4 Hard Destination mailbox address ambiguous
5.1.5 Hard Destination mailbox address valid
5.1.6 Hard Mailbox has moved
5.1.7 Hard Bad sender\’s mailbox address syntax
5.1.8 Hard Bad sender’s system address
5.2.0 Soft Other or undefined mailbox status
5.2.1 Soft Mailbox disabled, not accepting messages
5.2.2 Soft Mailbox full
5.2.3 Hard Message length exceeds administrative limit.
5.2.4 Hard Mailing list expansion problem
5.3.0 Hard Other or undefined mail system status
5.3.1 Soft Mail system full
5.3.2 Hard System not accepting network messages
5.3.3 Hard System not capable of selected features
5.3.4 Hard Message too big for system
5.4.0 Hard Other or undefined network or routing status
5.4.1 Hard No answer from host
5.4.2 Hard Bad connection
5.4.3 Hard Routing server failure
5.4.4 Hard Unable to route
5.4.5 Soft Network congestion
5.4.6 Hard Routing loop detected
5.4.7 Hard Delivery time expired
5.5.0 Hard Other or undefined protocol status
5.5.1 Hard Invalid command
5.5.2 Hard Syntax error
5.5.3 Soft Too many recipients
5.5.4 Hard Invalid command arguments
5.5.5 Hard Wrong protocol version
5.6.0 Hard Other or undefined media error
5.6.1 Hard Media not supported
5.6.2 Hard Conversion required and prohibited
5.6.3 Hard Conversion required but not supported
5.6.4 Hard Conversion with loss performed
5.6.5 Hard Conversion failed
5.7.0 Hard Other or undefined security status
5.7.1 Hard Delivery not authorized, message refused
5.7.2 Hard Mailing list expansion prohibited
5.7.3 Hard Security conversion required but not possible
5.7.4 Hard Security features not supported
5.7.5 Hard Cryptographic failure
5.7.6 Hard Cryptographic algorithm not supported
5.7.7 Hard Message integrity failure
9.1.1 Hard Hard bounce with no bounce code found. It could be an invalid email or rejected email from your mail server (such as from a sending limit).


As a note, the bounce codes displayed on your report page are the codes that our servers receive from the receiving mail servers.   It is important to know that it’s possible that these mail servers may provide codes that do not really reflect the true nature of the bounce.

More questions?

For more information about any feature of our Email Marketing software, please contact our Support Department. We would be happy to assist you.