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Bounce reasons and descriptions for Marketing Cloud Sends

Knowledge Article Number 000229837

Anytime a Marketing Cloud Send to one of your subscribers bounces, the recipient domain MTA sends us a bounce message with a bounce reason. This table describes each of those reasons along with a description.

Note: Actual bounce reasons may vary because each Domain Admin has direct control over the bounce messages relayed back to the sender. For more information about bounce handling, read our "Bounce Mail Management" documentation.


ID NumberDescriptionReason
1001ComplaintsYour email is blocked due to complaints.
1002SpamblockedThe remote mail server has rejected this message due to characteristics of spam.
1004ContentMessage was filtered due to content.
1005URL BlockEmails containing your URLs are blocked.
1009High Unknown Address Pct.Email is blocked due to the high quantity or percentage of unknown or inactive addresses on your list.
1010AuthenticationMessage lacks required authentication.
1999OtherThis email has been blocked by recipient.
2001User UnknownAddress is non-existent at the domain
2002Domain UnknownRecipient domain doesn't exist.
2003Bad AddressSyntax Email address in invalid.
2999OtherThis address does not accept mail.
3001Mailbox FullRecipient's mailbox is full or has exceeded storage allocation.
3002Inactive AccountAddress is temporarily unavailable.
3003Temporary Domain FailureReceiving domain temporarily unavailable.
3999OtherMailbox temporarily unavailable.
4001Server Too BusyReceiving email server is temporarily overwhelmed with delivery attempts, from you and other senders.
4002Data Format ErrorEmail is rejected due to formatting or line length errors.
4003Network ErrorConnection lost or timed out during delivery.
4999OtherFailed due to temporary failure or indecipherable bounce message.

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