Is the outgoing smtp server expected to notify sender of failure in upstream transfer giving this scenario?:
User A tries to send email message via his Outgoing SMTP (A-SMTP) server to recipient B. Outgoing SMTP (A-SMTP) server accepts message and notifies the sender of succesfull trasmit.
Hovewer when A-SMTP contacts the incoming SMTP server of recipient (B-SMTP) the B-SMTP rejects the message because A-SMTP is trying to use weak TLS cipher.
B-SMTP sees '403 4.7. 0 TLS handshake failed' with RST packet
A-SMTP sees in his mail log: status=deferred (Cannot start TLS: handshake failure)
