[collectd] huge values with tail plugin

[Manuel CISSE]

Hi all,

I'm using the tail plugin to monitor exim traffic and ssh failed/invalid
login.
My configuration (see below) is pretty much the same as in the man page,
but from time to time I have huge values (last was 229.1M for "Local
delivered") in the RRD database.

Does anybody what could be causing this behaviour? Any problem in my config?

regards,
Manuel

P.S.: relevant part of my config:
<Plugin "tail">
        <File "/var/log/auth.log">
                Instance "Failed SSH attempts"
                <Match>
                        Regex "Failed password"
                        DSType "CounterInc"
                        Type "counter"
                        Instance "Failed password"
                </Match>
                <Match>
                        Regex "Failed password for invalid user"
                        DSType "CounterInc"
                        Type "counter"
                        Instance "Invalid users"
                </Match>
        </File>
        <File "/var/log/exim4/mainlog">
                Instance "Exim"
                <Match>
                        Regex "S=([1-9][0-9]*)"
                        DSType "CounterAdd"
                        Type "ipt_bytes"
                        Instance "Transferred bytes"
                </Match>
                <Match>
                        Regex "\\<R=maildrop\\>"
                        DSType "CounterInc"
                        Type "counter"
                        Instance "Local delivered"
                </Match>
        </File>
</Plugin>