Please upload a new version of ssmtp: http://math.berkeley.edu/~schneck/cygwin/ssmtp/ssmtp-2.60.9-2.tar.bz2 http://math.berkeley.edu/~schneck/cygwin/ssmtp/ssmtp-2.60.9-2-src.tar.bz2
Corinna, this has an ssmtp-config which suggests linking /usr/sbin/sendmail to ssmtp; so go ahead and upload your new cron. Thanks! Robert