# middleware_error (/docs/reference/errors/middleware-error)



`EmailMiddlewareError` has code `middleware_error`, is not retryable, and exposes `phase`:

* `before_send`
* `after_send`
* `on_error`

The original exception remains the standard `cause`.

Hook exceptions do not produce this error because hooks are isolated and swallowed. Only middleware failures are delivery-visible.

A `before_send` failure happens before adapter dispatch. An `after_send` failure can occur after the provider accepted the message, so application recovery must not assume the email was unsent.