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SMTP Bounce Codes (Email Delivery Failure Codes)

Complete reference guide to SMTP bounce codes (email delivery failure codes). Learn about all bounce codes, their meanings, and how to handle them.

SMTP Bounce Code 4.2.1: Mailbox Temporarily Disabled

4-2-1-mailbox-temporarily-disabled

SMTP Bounce Code 4.2.2: Mailbox Full

4-2-2-mailbox-full

SMTP Bounce Code 4.3.1: Mail System Full

4-3-1-mail-system-full

SMTP Bounce Code 4.3.2: System Not Accepting Network Messages

4-3-2-system-not-accepting

SMTP Bounce Code 4.4.1: No Answer From Host

4-4-1-no-answer-from-host

SMTP Bounce Code 4.4.2: Connection Failure

4-4-2-connection-failure

SMTP Bounce Code 4.4.3: Routing Server Failure

4-4-3-routing-server-failure

SMTP Bounce Code 5.1.0: Other Address Status

5-1-0-other-address-status

SMTP Bounce Code 5.1.1: User Unknown

5-1-1-user-unknown

SMTP Bounce Code 5.1.2: Invalid Domain

5-1-2-invalid-domain

SMTP Bounce Code 5.1.3: Bad Address Syntax

5-1-3-bad-address-syntax

SMTP Bounce Code 5.2.0: Other Mailbox Status

5-2-0-other-mailbox-status

SMTP Bounce Code 5.2.1: Mailbox Disabled

5-2-1-mailbox-disabled

SMTP Bounce Code 5.2.2: Mailbox Full (Permanent)

5-2-2-mailbox-full-permanent

SMTP Bounce Code 5.3.0: Mail System Error

5-3-0-mail-system-error

SMTP Bounce Code 5.3.1: Mail System Full (Permanent)

5-3-1-mail-system-full-permanent

SMTP Bounce Code 5.3.2: System Not Accepting (Permanent)

5-3-2-system-not-accepting-permanent

SMTP Bounce Code 5.3.3: System Not Capable

5-3-3-system-not-capable

SMTP Bounce Code 5.4.1: No Answer From Host (Permanent)

5-4-1-no-answer-from-host-permanent

SMTP Bounce Code 5.4.2: Bad Connection (Permanent)

5-4-2-bad-connection-permanent

SMTP Bounce Code 5.4.3: Routing Server Failure (Permanent)

5-4-3-routing-server-failure-permanent

SMTP Bounce Code 5.4.4: Unable to Route

5-4-4-unable-to-route

SMTP Bounce Code 5.5.0: Other Protocol Status

5-5-0-other-protocol-status

SMTP Bounce Code 5.6.0: Other Media Error

5-6-0-other-media-error

SMTP Bounce Code 5.7.0: Security Status (Other)

5-7-0-security-status

SMTP Bounce Code 5.7.1: Delivery Not Authorized

5-7-1-delivery-not-authorized