Do you enter the username directly into the config file or throught the GUI? See http://lists.otrs.org/pipermail/otrs/2006-August/ 012068.html for the original post that said escaping the @-sign worked. Also note that that archived mail has "@" replaced by "_at_", the original mail has just "@".
I entered it in the GUI, in the admin area. Will check the post above.
Cool down or go get commercial support (http://www.otrs.com/). No need to panic, we're only trying to help you here.
I don´t panic, no prob. I am cool as someone can be cool when his server-provider just got bankrupt and all machines are off !!!! :-))) Have you heard about Colossus?? I had my servers there.. geeez... all off... :-(( I appreciate your help, I am just worried about the help from the new server-provider, who responds me with "yes" and "no", but nothing else... :-( Thanks for your effort! Marc