How to _mandatory upgrade to TLS_ with sieve or other cyrus services?

[Thomas Harding]

Thomas Harding wrote:
> I use imaps with a single CA (home made), which make me able to filter
> users basing on trusted-CA signed certificates.
> How to disable non-TLS sessions on sieve, and more generally for any
> cyrus service?
>   
Answering to my own question: by reading carefully imapd.conf man page :)
combining:
sasl_mech_list: PLAIN  LOGIN
with:
 allowplaintext: no
will do the trick.