Will I lose emails if my Exchange Server happens to be down when POPcon tries to send emails there?
No emails will not be lost. If POPcon can't reach your Exchange server it will simply retry until the server is reachable again. POPcon stores all messages in temporary files on your harddisc - your emails are safe even if you shutdown the machine that runs POPcon.
We designed POPcon to never lose any email under no circumstances whatsoever - even when you yank the power cord while POPcon downloads emails or while it forwards emails to exchange.