WelcomeBack15%
I'm not exactly happy to post this since I had a fairly unpleasant experience and would not recommend this service to anyone but I'm posting this in case you're at the point of no return like me (you didn't realise how bad their service is until you used it). I decided to try using some old voucher codes that were posted here in the past and this one still seemed to work.
If you are reading this and have been thinking about using ShopMate, just don't. Here's a Whirlpool topic I wish I had read before using ShopMate. In my particular circumstance, I feel that I have been massively overcharged due to their incompetence in calculating the weight of my package properly. (Not going to bother explaining here in further detail since I don't think this is the place for it.) With this coupon I ended up paying $44 rather than $52 on my items that come to around 0.65kg. (The items themselves are not that overly large either so I doubt their total cubic weight is accurate.) Wew!
EDIT: I just want to say that as with all of these types of services, YMMV. Don't let my experience deter you completely. I wrote the above when I was a little pissed off. Maybe you might have a good experience using ShopMate. Still, make sure to check out alternatives like Shipito as others have mentioned.
As an alternative I've used shipitto in the past, and they've been pretty good from North America (TNT express shipping was cheap too!)