Hi Samtuke and Dragonrider,
Thanks a lot for your reply. I think that the problem is not phplist, but custom made programms that take care for importing rrs feeds from WordPress into the newletter. Next Friday I will take a look at it with a php- and mysql-specialist and I hope we will find a solution. After that I will update to 3.3.1 and find out if everything will still work ok.
Kind regards, Vincent