Decrease Delivery Attempt Log Verbosity

When the opt.quieter_qmail_send_logfiles boolean setting is turned on, GreenArrow logs less information in the delivery attempt logfiles. This omits information about new messages received, delivery attempts beginning and messages finished. All information about delivery attempts completing is still logged.

To enable, run:

echo 1 > /var/hvmail/control/opt.quieter_qmail_send_logfiles
hvmail_init restart_send_processes

To disable, run:

echo 0 > /var/hvmail/control/opt.quieter_qmail_send_logfiles
hvmail_init restart_send_processes

This is disabled by default.