After a long chat with the staff at my local po, they seem to think it is ok to post markers, but would not commit to a definite yes or no. One odd mention once it was fine if it was new but I never pressed the matter. However they always ask me what's in the package, and I always tell them, they never say 'that item is prohibited'... Pretty sure all po have to ask what's in the parcel now...
Anyhow, I never had problems sending via special delivery, but did I read on here somewhere is having a bit of an issue?