call and or email and ask them?

ermat: Not much help there. They direct you to restricted items document which states printer cartridges only. I just want to make sure toner powder is not in this catagory.

The list here explicitly states "ink cartridges", not "printer cartridges". Toner is not ink, so not explicitly prohibited.

The trouble with YouShop is that packages are handled by a third party. The YouShop T&C state that if they "consider that any of the items in Your Parcels ... are Prohibited Items", they will make you liable for costs associated with disposing of Prohibited Items.

Fortunately, they define Prohibited Items very clearly and the dictionary definition of ink is on your side, so I'd expect you'd come out on top of any dispute, but is it really worth the hassle?

I wouldn't even try... This restriction came about because of the 2010 plot to bring down an aeroplane, which used toner cartridges to host an explosive device.

If you try, I don't see people in the USA making much distinction between ink and toner, despite what the dictionary says.