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Act Marketing Automation - Bounce Code Reasons

One of the important things to do after sending out a marketing campaign is to find and fix (if possible) emails that have been reported as bounced.  There are a variety of reasons why emails bounce.  A mailbox can be full.  A person has moved on and the email is no longer valid. The email server you are trying to send to is not live or working anymore.  It is worth while to take the effort to look at these bounced emails - these are not opt outs.  The person you are trying to reach is still somewhere - you just have to figure out where. Knowing why the email bounced is your key.

The suppression list located under the Admin menu in Act Marketing Automation shows emails that have bounced or been flagged as opt outs.  You can export this list to Excel and that export will include the reason codes, if known, for bounces.

However, there is not a set list of reasons for each bounce code or message. This is due to the code and reason being set on the receiving server, not on the Swiftpage server, i.e. each server that receives an email that bounces will send its own bounce code which may differ from other servers.

Most codes do have a common reason, so the below tables can be used. However, please note that the tables below are not all encompassing and are meant as a general guide.

There are two types of bounce codes, traditional codes which are 3 digits with no separation, and enhanced codes which are 3 digits separated by a period.


Code Common reason
000 Domain name does not exist
421 Service not available, closing transmission channel
450 Requested mail action not taken: mailbox unavailable (e.g., mailbox busy)
451 Requested action aborted: error in processing (e.g., unable to reach destination system, bad email address, includes unspecified reasons as well)
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments (e.g., invalid sending email address, invalid recipient address)
502 Command not implemented
503 Bad sequence of commands
504 Command parameter not implemented
550 Requested action not taken: mailbox unavailable (e.g., mailbox not found, no access, or command rejected for policy reasons)
551 User not local; please try
552 Requested mail action aborted: exceeded storage allocation
553 Requested action not taken: mailbox name not allowed (e.g., mailbox syntax incorrect)
554 Transaction failed

Mail admins may modify messages sent with the codes which may give more information than the above from their server; Information from RFC2821 http://www.rfc-editor.org/rfc/rfc2821.txt


Enhanced codes will typically begin with a 2, 4 or 5. This first digit indicates the following:

2.X.X Success
4.X.X Persistent Transient Failure
5.X.X Permanent Failure

The codes shown below are most commonly seen beginning with 5.

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

Mail admins may modify messages sent with the codes which may give more information than the above from their server; Information from RFC3463 http://www.rfc-editor.org/rfc/rfc3463.txt

Hard vs Soft Bounces

When an email sent from one of your Act! Marketing Automation campaigns bounces, it can be classes as a soft or a hard bounce. This will affect how AMA handles the bounce:

  •  ‘Soft’ bounces are where an email couldn’t be delivered to an email address for temporary reasons.  The email address sent to is valid and the mail server was reached but the email couldn’t be delivered, for example because the recipient’s inbox was full or the email was too large.

  • ‘Hard’ Bounces are where an email couldn’t be delivered to an email address for permanent reasons.  There can be a number of reasons for this but examples of the more common ones are that the email domain doesn’t exist or the email address doesn’t exist.

Hard bounces and Admin bounces are fed back to Act! servers and flagged so that emails are prevented from being sent to these email addresses. Hard bounces CANNOT be removed from your suppression list manually, instead it would require a call to the Act! technical support team. This can only be done on an ad-hoc basis, Swiftpage cannot remove hard bounces in bulk in order to protect their sender reputation.

Patricia Egen Consulting, LLC

803 Creek Overlook, Chattanooga, TN 37415
Main office: 423-875-2652 • Arizona office: 480-788-7504 • Florida office: 754-300-2827