STARTTLS bypass via PREAUTH

When mutt is configured to use STARTTLS and the IMAP server responds with "* PREAUTH ...", Mutt will not initiate the STARTTLS transition and proceed in plaintext. This is a similar issue to CVE-2014-2567 and CVE-2020-12398. No credentials are exposed, however, email data (drafts, sent emails, ...) are exposed in plaintext.