Troubleshooting Permanent Bounce Errors for Blocked Outbound Recipients

When an email sent through BoldDesk returns a permanent bounce, the affected recipient address may be blocked from receiving further outbound emails. This restriction helps protect email deliverability by preventing repeated delivery attempts to invalid, disabled, rejected, or suppressed addresses.

When a recipient address is blocked, BoldDesk cannot send agent replies, automated notifications, or system emails to that address until the restriction is removed.

This article applies only to outbound emails sent through BoldDesk’s email delivery service.

If your organization uses a custom SMTP server, review delivery failures directly in your SMTP server or email provider. After BoldDesk hands the message off to the custom SMTP server, it cannot retrieve the final delivery, bounce, or failure status.

Before You Begin

Locate the affected delivery record and copy its Error Details.
You can find the delivery error in either of the following locations:

For one ticket message, open the message’s Email Delivery Status.
For organization-wide failures, go to Admin > Audit Logs > Email Failure Logs.

For complete instructions, learn more about:

If you need information about transient and permanent bounce classifications, refer to Understanding Email Delivery Failures: Transient & Permanent Bounces.

Permanent Bounce Scenarios

Use the exact response shown under Error Details to identify the required corrective action.

Error Details	What the Response Means	Required Verification
`550 5.1.1 The email account that you tried to reach does not exist`	The recipient’s mail server reports that the mailbox does not exist.	Confirm the complete email address with the recipient. Verify that the mailbox is active before requesting unblocking.
`550 5.1.1 Recipient address rejected: User unknown in virtual mailbox table`	The recipient server cannot find the address in its virtual mailbox configuration.	Ask the recipient’s email administrator to verify that the mailbox or alias exists and is correctly provisioned.
`Amazon SES did not send the message to this address because it is on the suppression list for your account`	The email-delivery provider did not attempt delivery because the address had already been suppressed following an earlier bounce or complaint.	Locate the earlier failure, confirm that the mailbox is valid and active, and verify that the recipient expects to receive BoldDesk emails.
`550 5.4.1 Recipient address rejected: Access denied`	The recipient’s email environment rejected the message because of an access, routing, mail-flow, or security restriction.	Ask the recipient’s email administrator to review the message trace, transport rules, mail-flow rules, security gateway, anti-spam policies, and sender restrictions.
`550 Invalid Recipient`	The recipient server does not recognize or accept the supplied email address.	Confirm whether the address exists as an active mailbox, alias, distribution group, or forwarding address. Update the recipient address in BoldDesk if the original address is incorrect.
`554.30 This mailbox is disabled`	The mailbox exists but has been disabled by the recipient’s email provider or administrator.	Ask the recipient’s email administrator to reactivate the mailbox or provide another active email address.
`552 1 Requested mail action aborted, mailbox not found`	The receiving system cannot locate or route the message to the mailbox.	Ask the recipient’s email administrator to verify mailbox provisioning, aliases, forwarding configuration, and mail routing.
`550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup`	The receiving environment cannot resolve the SMTP address to an active recipient object.	Ask the recipient’s email administrator to verify the primary SMTP address, aliases, proxy addresses, mail-enabled object, and directory synchronization.

Do not request unblocking until the recipient address and the underlying mailbox, routing, or security issue have been verified. Removing a restriction without correcting the original failure can cause the address to bounce again.

Request Unblocking

After the underlying issue has been corrected, contact BoldDesk Support and provide:

BoldDesk portal URL
Affected recipient email address
Ticket ID, if available
Email Message ID or Message ID
Delivery date and time
Bounce Type
Complete Error Details
Confirmation that the mailbox exists and is active
Corrective action completed by the recipient or email administrator

You can contact BoldDesk Support through:

Email: [email protected]
BoldDesk Support Portal

BoldDesk Support will review the delivery failure and remove the outbound restriction when appropriate.

Correcting the recipient’s mailbox or email-server configuration does not automatically remove an existing outbound restriction or suppression entry. The address must be reviewed and unblocked before BoldDesk can resume sending emails to it.

Verify Delivery After Unblocking

After BoldDesk Support confirms that the address has been unblocked:

Confirm that the recipient address on the ticket is correct.
Send one controlled public reply from the affected ticket.
Open Email Delivery Status for the new message.
Confirm that the recipient displays a Delivered status.
Ask the recipient to confirm that the message was received.

If the message bounces again, do not repeatedly resend it. Record the new Bounce Type and Error Details, and return the failure information to the recipient’s email administrator or BoldDesk Support.

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