Determine the method used to send email. Allowed values are "off", "relay", "pipe", "dir", "db", and "stdout". The "off" value means no email is ever sent. The "relay" value means emails are sent to an Mail Sending Agent using SMTP located at email-send-relayhost. The "pipe" value means email messages are piped into a command determined by the email-send-command setting. The "dir" value means emails are written to individual files in a directory determined by the email-send-dir setting. The "db" value means that emails are added to an SQLite database named by the* email-send-db setting. The "stdout" value writes email text to standard output, for debugging.