Okay, I still don't understand why my folder-hook did not work. Just like setting the hostname has to be done very early. If someone is interested in my muttrc as to why that is, I will post it here.
On the other hand, working with folder-hooks in conjunction with my newsserver works perfectly now: I get to keep a local message-copy and adjust my hostname accordingly. Thanks for the help! (Now I can file a report about a primary problem via newsgroup :P ) -- Time flies like the wind, but fruit flies like bananas.
