## TL;DR

Remove the address from every mailing list immediately, and add it to your suppression handling. If this was a transactional email (receipt, password reset), surface the failure to the sender in your app so they can fix the address they typed.

## Steps

1. The recipient's mail server permanently rejected the email. This is a hard bounce. The address is invalid and will never accept mail.

2. Remove the address from every mailing list immediately, and add it to your suppression handling. Never retry a hard bounce.
2. Record the bounce subtype if present: General (provider sent a hard bounce) or NoEmail (address does not exist or could not be determined). Both mean stop.
3. If this was a transactional email (receipt, password reset), surface the failure to the sender in your app so they can fix the address they typed.
4. Check your suppression list: Resend adds hard-bounced addresses automatically.

3. Continuing to send to hard-bounced addresses. It destroys your sender reputation with providers, which hurts deliverability for your good addresses too. Also, do not confuse this with `email.delivery_delayed`: a soft bounce may resolve, a hard bounce never does. Resending to a bounced address is never the fix.

## When to use

You are seeing this: The recipient's mail server permanently rejected the email. Use this skill when you run into "Resend event: email.bounced, hard bounce, stop mailing that address now".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Edge cases

- Also, do not confuse this with email.delivery\_delayed: a soft bounce may resolve, a hard bounce never does.