Eu tenho em /etc/postfix/main.cf:
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination
e o SASL parece estar funcionando:
$ testsaslauthd -u yang -p ... -f...
19.10.2010 / 07:28