We don't store copies of plaintext emails indefinitely (it's obviously exists in the mail pipeline before processing). This statement is based on trust, as it would be for literally any email provider. That said, if we did store mails long term, they would be vulnerable to subpoena, and thus would almost certainly get out at some point, which would be very bad for us. So we have every incentive to actually discard plaintext, just like we say we do.
Obviously this does not apply to internal or external messages that are encrypted, so the real solution is to receive less unencrypted mail, which is exactly what today's announcement is about.
Obviously this does not apply to internal or external messages that are encrypted, so the real solution is to receive less unencrypted mail, which is exactly what today's announcement is about.