Geoffrey T. Cheshire found a neat little bug that effected Cygwin users that needed SMTP AUTH. If you were trying to use SMTP AUTH with Cygwin and you were having problems, please upgrade to version 2.3.1. Alternately, you can do 1 of 2 work arounds if you do not want to upgrade. Workaround 1: Add a comment to the end of each SMTP_* line. For instance: SMTP_USER = 'username' # Comment SMTP_PASS = 'password' # Comment Workaround 2: User the --smtp-user and --smtp-pass command line options and comment SMTP_USER and SMTP_PASS out of the email.conf file. http://email.cleancode.org Email - Command line SMTP Client for Unix