Stalwart 0.14 disables PLAIN/LOGIN on non-TLS ports by default: - [imap.auth] allow-plain-text = true → unblocks IMAP LOGIN - [session.auth] mechanisms + allow-plain-text → advertises PLAIN/LOGIN on SMTP Also fix test: SMTP authenticates as "alice" not "alice@localhost" (Stalwart SMTP auth accepts username without domain, unlike IMAP login) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>