Bounce and complaint forwarding
Use bounce and complaint forwarding to send delivery failures and spam complaints to another system by email. Each project can use one verified forwarding address. You can use this feature on all plans, with or without webhooks.
Set a forwarding address
You need permission to manage the project.
- Open the project and select Settings.
- In Project settings, find Bounce and complaint forwarding.
- Enter the email address that will receive the reports.
- Select Save changes. The verification dialog opens.
- Get the six-digit code from the verification email. Enter the code in the dialog.
- Select Verify forwarding address.
The dialog closes after verification. A check icon and Verified appear below the address.
If you close the dialog before verification, select Verify address below the address to open it again.
The code expires after 15 minutes. You can try a code up to five times. Select Resend code to request a new code. Wait at least one minute between requests. You can request up to five codes per hour.
Lettermint sends reports only for new events received after verification. It does not send reports for earlier events.
Report formats and sources
Delivery failures use the Delivery Status Notification format, or DSN. Spam complaints use the Abuse Reporting Format, or ARF.
The email comes from Lettermint. Report fields identify the source of the delivery result or complaint.
| Event | Report content |
|---|---|
| Delivery failure report from a receiving provider | The DSN keeps the provider's reporting server, recipient, status, and diagnostic fields. |
| Permanent SMTP rejection | The DSN identifies the Lettermint sending server and, when available, the rejecting server and its response. |
| Delivery expiry | The DSN states that the Lettermint sending server stopped delivery attempts. It includes the final status and available diagnostic details. |
| Provider spam complaint with an ARF report | The ARF keeps the provider's report fields and source identity. |
| Accepted complaint without a provider ARF | Lettermint creates an ARF from the complaint evidence. It identifies Lettermint as the report generator and names the complaint source. Manual complaints are marked as manual. |
In a DSN, Reporting-MTA identifies the server that reports the result. It does not always identify the server that rejected the message. Remote-MTA identifies the remote server when that information is available.
Each email uses multipart/report. It contains an explanation, report fields for software to process, and selected original headers when available. Report identifiers let your system match the report to its project, message, recipient, and source event.
Reports exclude original message bodies, attachments, Bcc headers, and internal tokens. If required evidence is missing, Lettermint does not send a report.
Change or stop forwarding
To change the forwarding address, enter a different address and select Save changes. Lettermint cancels pending reports for the old address. Verify the new address to start forwarding again.
To stop forwarding, clear the address and select Save changes.
A report submission that has already started can still reach the old address. Lettermint cannot recall a report after the mail server accepts it.