Checkout this post SSL_connect error to 127.0.0.1[127.0.0.1]:10025: -1 - #4 by martijn
I think this is the same issue that you have, i.e., you changed the default which will then also require TLS when connecting to the back-end (which is not supported).
You need to change the security level only for a specific service.
In your case, do not add
smtp_tls_wrappermode = yes