Postfix configuration, SASL, and xsasl_cyrus_server_get_mechanism_list: no applicable SASL mechanisms

This almost drove me crazy today. Did everything correctly (i thought), but always got the above error.

Problem was: if you say

smtpd_sasl_security_options = noanonymous, noplaintext

in main.cf, and

 mech_list: PLAIN LOGIN

in smtpd.conf, then of course there's no mechanism that matches if you don't use SSL.

Bah!