substack/node-smtp-protocol — pull request #26 by rusintez (2014-08-05 16:25:40+00:00)
Title: reset greeting when upgrade to tls

Ref: 5.2 Result of `STARTTLS` command [rfc2487](https://www.ietf.org/rfc/rfc2487.txt)

> The server MUST discard any knowledge
obtained from the client, such as the argument to the EHLO command,
which was not obtained from the TLS negotiation itself.

> The client SHOULD send an EHLO command as the
first command after a successful TLS negotiation.