Fetchmail 5.1.0 will send an email warning message and abort
if it gets an authentication failure when running in daemon
mode. With frequent polling, POP3 authentication failures
are not uncommon. Fetchmail 5.1.0 is not usable for me
because of this problem, and I have reverted to the 4.5.8
distribution from Red Hat 5.2.
The vendor (Eric Raymond) has released newer versions of
fetchmail which, according to the on-line documentation, can
be configured to tolerate authentication failures without
aborting. Please make a newer version available to overcome
this issue. See http://www.tuxedo.org/~esr/fetchmail/NEWS
The current revision of fetchmail in Raw Hide (which will be used in the next
release unless it gets updated further) is 5.2.5.