The relay connection only had `secure`, so with `secure: false` nodemailer still upgraded to STARTTLS whenever the server advertised it, and there was no way to talk cleartext to such a server. Pass nodemailer's `ignoreTLS` through as `ignoreTLS` on the relay config, wired to --outgoing-ignore-tls / MAILDEV_OUTGOING_IGNORE_TLS / `outgoingIgnoreTls`.