I'm trying to understand how the command STARTTLS in IMAP works exactly and what becomes different when it's sent. After I've sent the command STARTTLS before login process and received the response OK Begin TLS negotiation now as a client, does  anything change for me as a client in the futher communication, that is, the format of the requests and responses, some additional information, etc?I mean the API level, not the lower levels.
What becomes different for a client after the command STARTTLS is sent and a response received
ssl;imap