« Dec 26 17:54:17 localhost postfix/smtpd[16304]: warning: SASL authentication failure: Internal Error -4 in ../../lib/server.c near line 1757
Dec 26 17:54:17 localhost postfix/smtpd[16304]: warning: SASL authentication failure: Internal Error -4 in ../../lib/server.c near line 1757
Dec 26 17:54:17 localhost postfix/smtpd[16304]: warning: SASL authentication failure: Internal Error -4 in ../../lib/server.c near line 1757
Dec 26 17:54:17 localhost postfix/smtpd[16304]: warning: xsasl_cyrus_server_get_mechanism_list: no mechanism available
Dec 26 17:54:18 localhost postfix/smtpd[16304]: fatal: no SASL authentication mechanisms
Dec 26 17:54:18 localhost postfix/master[5159]: warning: process /usr/lib/postfix/smtpd pid 16304 exit status 1
Dec 26 17:54:18 localhost postfix/master[5159]: warning: /usr/lib/postfix/smtpd: bad command startup -- throttling »

Et 1 an et demi après, je me réponds à moi-même : il faut installer le package libsasl2-modules...