Having your android device unlocked will definitely results in password disclosure.

• Open Your IMAP/SMTP settings.
• Change address of your SMTP mail server to a computer under your control and make sure "Authorisation" is checked.
• Fire up netcat, pretend to be a mail server and ask for authorization.
• Let android try to authentificate and get your victim's password..

The problem is, even Android 7.1 is vulnerable. All you need is someone's phone in your hand, considering it's not locked.