Well, you may be right, but there ware several servers on that blacklist until Monday evening, and all of them 'dissapeared'. But the mistery is solved already, this morning the server I used to check on (and again: several others) is listed again. Thank you anyway for taking the time to react.
Hmm, it looks like the Gmail servers have been removed from the blacklist? Did something change and is the matter somehow resolved, has Gmail silently become an exception or did the listing just expire and is it a matter of time before the Gmail servers will be back on the list? By the way: bad coincidence this had to happen right after I published an item about it on my website (in Dutch).