# X_MAIL_EVENT_INVALID

## Means

a delivery notification is not a shape this receiver reads

## Typical cause

too large, not UTF-8, not JSON, a missing envelope or notification field, or a bad timestamp (meta.problem says which)

## Fix

`aws sns list-subscriptions-by-topic --topic-arn '<your topic arn>'` — only the provider should post to this route

[Mail](/error-codes#mail)