Email Bounce Reasons

  • Updated

When your email doesn't successfully reach its intended audience, it may have hard-bounced, soft-bounced, or been suppressed by the recipient's mail server. Act-On's Sent Message Report can help you understand why. When viewing a Sent Message Report, click the Not Sent / Suppressed count to see a list of reasons (called bounce codes) for why your message failed to send.

Read below for more information about bounce reasons that may appear in your Sent Message Reports.

Other factors may affect your email's deliverability. Find more Connect resources on email deliverability and sender reputation here.

Bounce Reasons

Reason Explanation
Bad mailbox A hard bounce; usually due to an invalid email address.
Policy-related A hard bounce; usually due to a specific security setting that the recipient's organization has set.
Bad domain or bad configuration

Act-On is having trouble communicating with the recipient domain. This can happen because:

  • A previous Act-On message-send received a generic response from the recipient domain, causing the system to classify this as a bad domain
  • There is a network or server issue occurring on the receiver's side
Message expired
No answer from the host
Act-On will attempt to send each email for up to 36 hours if there is no response from the recipient’s server. After that time, we will classify this message as a soft bounce with "Message expired" or "No answer from host".
Prohibited system address
Role based-address

You're trying to send to a generic email alias that hasn't been added to your allowed list. Generic email addresses or aliases are suppressed by default because they are well known for generating spam complaints and hurting message deliverability.

Routing errors The server could not route the message correctly to the proper inbox. The recipient's email host may be experiencing a temporary outage.
Spam-related The recipient's incoming mail server considers this message to be spam.
Quota issues The recipient's mailbox has reached an internal storage limit and cannot accept any incoming messages. 
Bad Connection The recipient's mail server was unable to accept the message due to a time-out or inadequate connection quality.
Invalid address The email address may be misspelled or improperly formatted.
Relaying issues This may be due to a recipient server issue. Usually, Act-On has found the email address but is having trouble communicating with it.
Possible spam trap

Act-On suspects the recipient domain is used to expose spammers, who add email addresses to their lists without permission. They may also be used to identify marketers who do not clean or maintain their lists adequately.

If you think that there are email addresses incorrectly associated with this value, contact support so they can be removed from the list.


Message bounces are marked "Other" when they do not fit into any of the above categories. "Other" bounces may be caused by:

  • Message size restrictions
  • Permission or authorization-based bounces
  • Other unspecified technical issues

If you're seeing multiple failed messages with "Other" listed as the bounce reason, please contact Act-On Support for additional help to identify the cause.

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