Since Front End PM PRO version 10.1.3 you can use POP3 feature for your incoming messages instead of email piping.
In some server email piping setup is too difficult. In some server email piping is not allowed. So we have added POP3 feature to overcome this limitation.
POP3 use cron job for incoming messages. It query your email inbox every after set time (by default per hour) and any new email will be imported as message if every check pass.
POP3 inbox email will be deleted after process. So it is better not to use POP3 email address for any other purpose.
Go to Dashboard > Front End PM PRO > Settings > Emails > Email Piping/POP3 > Enable and set as POP3
For other information see your email address setup instruction.