sasl_log_t - The SASL logging callback
       #include <sasl/sasl.h>
       int sasl_log_t(void *context,
                     int level,
                     const char * message);
       sasl_log_t is used to log warning/error messages from the SASL library.
       If not specified syslog will be used.
       SASL callback functions should return SASL return codes. See sasl.h for
       a complete list. SASL_OK indicates success.
       RFC 2222
       sasl(3), sasl_callbacks(3), sasl_errors(3)