sends all *.eml files in folder via /usr/sbin/sendmail wrapper optionally archiving (or removing) sent files.
Recepients are determined automatically from "To:" lines in .eml files.
you should run it from cron job via line like:
# m h dom mon dow user command */15 * * * * user /usr/local/bin/send-emails-from-folder sender@example.org /home/user/emails /home/user/archive