Bounce

This event webhook is called whenever one of your emails bounces. Emails bounce for various reasons.

Note: Upon a hard bounce, the contact is automatically added to the suppression list.

List of Body Attributes

This table shows the list of parameters present in the payload and their explanations.

Parameters	Data Type	Description
webhook_name	String	Name of the webhook you configured.
webhook_id	String	ID of the configured webhook.
action	String	Name of the event.
actionType	String	Type of bounce, which can be hard bounce or soft bounce.
data	JSON Array	An array of data about the events
bounce_code	String	The bounce code provided by the recipient email service provider.
bounce_type	String	Type of bounce, which can be hard bounce or soft bounce.
bounce_extended_code	String	An additional code that indicates a specific case of bounce. This is also returned by the recipient email service provider.
bounce_reason	String	Reason for the bounce.
action_time	Long	Time (in UTC milliseconds) at which the bounce event happened.
sending_ip	String	The IP through which the mail was attempted, but was bounced.
contact_id	Long	ID of the contact to which the mail was attempted, but was bounced.
contact_email	String	Email address of the contact to which the mail was attempted, but was bounced.
rcpt_domain	String	The domain of the recipient.
rcpt_additional_data	JSON Object	Additional data of the recipient that was provided by you in Transmission API or Recipient List API.
from	String	Indicates the sender address.
subject	String	The subject of the transmission.
message_id	String	The message ID of the email that got bounced.
transmission_name	String	The name you provided for the transmission in Transmission API.
injected_time	Long	Time (in UTC milliseconds) at which the transmission was created.
transmission_id	Long	The ID of the transmission.
zuid	Long	The ID of the user that sent the transmission API request.

Bounce Reasons

Bounce Extended Code	Bounce Reason	Description
4.1.1	Temporary mailbox address failure	The recipient's email address could not be found temporarily.
4.1.2	Temporary domain address failure	Temporary issue with the domain name of the recipient.
4.2.0	Mailbox temporarily unavailable	The mailbox is temporarily unavailable, possibly due to a server issue.
4.2.2	Mailbox full	The recipient's mailbox is full and cannot accept new messages.
4.2.3	Message length exceeds	Indicates that the message contains attachments or text that exceeds the system's message length limit.
4.2.4	Mailing list expansion problem	The mailbox is a mailing list address and the mailing list was unable to be expanded.
4.3.1	Mailsystem full	The mail server is temporarily out of resources.
4.3.2	System not accepting network messages	This could be due to various reasons, such as an unplanned shutdown, system maintenance, or excessive load.
4.3.3	System not accepting messages	This could be because the message contains features not supported by the receiving system.
4.3.4	Message too big for system	Message size limit has been exceeded.
4.3.5	System incorrectly configured	The server configuration might have errors or incorrect values.
4.4.1	No answer from host	Temporary failure due to network issues between servers.
4.4.2	Bad connection	Mail server timed out while trying to connect to the recipient’s server.
4.4.3	Directory server failure	This error indicates that the email was temporarily delayed or rejected due to issues with routing the message through the recipient's mail server or across intermediate servers.
4.4.4	Unable to route	Indicates network issues, including broken routing.
4.4.5	Mailsystem congestion	The message was undelivered due to the recipient's email network being congested or overloaded.
4.4.6	Routing loop detected	A routing loop was detected due to a network issue, and the email message was forwarded repeatedly.
4.4.7	Delivery time expired	Indicates that an email could not be delivered to the recipient's mailbox within a specified time. It suggests a delay rather than a permanent failure.
4.4.8	MX policy error	This error usually indicates an issue with the destination domain's MTA-STS policy not containing the MX host.
4.5.1	Invalid command	The message was undelivered due to an invalid command by the sender's email provider.
4.5.3	Too many recipients	The message has more than 200 SMTP envelope recipients from the same domain.
4.5.5	Wrong protocol version	This error indicates that there was a protocol mismatch or error during the communication between the sending and receiving mail servers.
4.6.0	Content not accepted	This error occurs when the recipient’s mail server encounters an issue with the message content, such as encoding, encryption, etc.
4.6.1	Media not supported	This error indicates that the email was temporarily rejected because the receiving server could not process the media type or content format of the message.
4.7.1	Delivery not authorized	The sender may not be authorized to send to the destination.
4.7.2	Mailing list expansion problem	The recipient's email provider has blocked your email address from posting messages to this mailing list.
4.7.26	Authentication problem	This error indicates that the message was not delivered due to SPF or DKIM failures.
4.7.7	Message integrity failure	This error indicates that the message was not delivered because it was corrupted or altered.
4.7.8	Authentication problem	This error indicates that the message was not delivered due to an incorrect username or password provided by the sender's email system.
4.7.10	Encryption needed	The message was rejected because it was not encrypted, but encryption was expected.
4.7.12	Password transition needed	This error indicates that the message requires password for authentication.
4.7.15	Priority level too low	This error indicates that the message has not yet been delivered due to a priority level lesser than which is acceptable by the email systems.
5.1.1	Bad destination mailbox address	The recipient's email address doesn't exist.
5.1.2	Bad destination system address	The domain part of the recipient's email is invalid or cannot be found.
5.1.3	Bad mailbox syntax	The email address format is incorrect.
5.1.4	Destination mailbox address ambiguous	The message could not be delivered because the recipient's email address is associated with more than one inbox.
5.1.5	Destination address invalid	It often occurs due to the recipient address being misconfigured, corrupted, or unavailable for routing.
5.1.6	Destination mailbox address has moved	The email address has changed, and no forwarding address is available.
5.1.8	Spam mail rejected	The account has been blocked for sending too much spam.
5.1.10	No MX for recipient	The recipient's <SMTP Address> wasn't found by SMTP address lookup.
5.2.1	Mailbox disabled	The recipient’s mailbox is disabled, possibly due to inactivity or deactivation.
5.2.2	Message quota exceeded	The recipient’s mailbox is full and cannot accept new messages.
5.4.1	Message rejected	This error is caused by mail server or DNS misconfiguration.
5.4.6	Routing loop detected	A configuration error has caused an email loop.
5.4.8	MX policy error	This error usually indicates an issue with the destination domain's MTA-STS policy not containing the MX host.
5.5.2	Syntax error	The sender's email address syntax is invalid.
5.5.3	Too many recipients	There were too many recipient addresses in the "To", "CC", or "BCC" field.
5.7.1 5.7.12	Authentication failure	The email was rejected due to permission issues (e.g., sender is not authorized).
5.7.13	User account disabled	The message could not be delivered because the email account for sender's email is disabled.

Sample payload for a bounce event

Copied{
  "webhook_name": "Bounce webhook",
  "webhook_id": "1314909000000063002",
  "action": "bounce",
  "actionType": "hardBounce",
  "data": [
    {
      "bounce_extended_code": "5.1.2",
      "bounce_type": "hardbounce",
      "bounce_code": "554",
      "bounce_reason": "bad-domain",
      "action_time": 1725543459000,
      "sending_ip": "135.84.83.99",
      "contact_id": 1314909023300000144084,
      "contact_email": "john.doe@zylker.com",
      "rcpt_domain": "zylker.com",
      "rcpt_additional_data": {
        "country": "JP",
        "ph": "1239333320"
      },
      "from": "\"Aaron Fletcher\" <aron@zylker.com>",
      "subject": "Summer is here",
      "message_id": "<zcb.3z48a08b0c5ad7835216d2d705c1539aa2a44504764ccc7f4bbeceff75d3b82de0.1123f7ec4d0f91a09.1725514638987@bounce.zylker.com>",
      "transmission_name": "My first Email API Campaign",
      "injected_time": 1725543431000,
      "transmission_id": 1314909000000112344068,
      "zuid": 8575431221455
    }
  ]
}