fetchmail keep some, not all mails on server

[basti <black.fledermaus@arcor.de>]

Hello @all,

I run a fetchmail daemon on my router.
Debian Version 5
Fetchmail Version 6.3.9-rc2+GSS+NTLM+SDPS+SSL+NLS+KRB5

My config looks like

# Configuration created Mon Jun 10 11:55:32 2002 by fetchmailconf
#set postmaster "postmaster"
#set bouncemail
#set no spambounce
#set properties ""

# own Log
set no syslog
set logfile /var/log/fetchmail.log
# mit preconnect und postconnect we get the date in the logfile

# fetch mails
....

There is no "keep" or "no keep" option set so fetchmail should delete
every received mail.
There is also no limit set in the config.

Some mails with a size round of 900 bytes keep on the server and some
mails with round 5000 bytes are delete.
I see no schema when a mail in keep and when not.

Can somebody explain this behaivior?
Or/ And can somebody tell me the right option to solve this?

I dont want so get allredy fetched mails a 2nd time.

is "no keep" the right one? -- is there a global option? (There are
round 100 mail addresses)
or is --flush the right one?
(http://www.fetchmail.info/fetchmail-FAQ.html#O14)


Thanks for any help.
Basti