I've had some responses from other crafters out there who have been targeted by this scam too. And I just got another email, this time from firstname.lastname@example.org that had basically the exact same text in the body, except instead of Katie Johson, it was Mary Vagner. I'll post the entire email here so you can see it.
"Hello there, I want to buy some good from your company to my new store in Australia, I will like to know if you accept credit card and ship internationally as I have got new shops opening in other part of the world. So please let me know if you can assist me with the order I will await your prompt response as soon as you receive this mail,I will be very glad if you treat this email with good concern... You can reply back to ...................email@example.com.......... Love from Mr and Mrs Vagner"
The strange grammar should tip you off right away. Thanks to Amber from Tea Cozies by ElDonna http://byeldonna.com for tracking this email down--it originated from Nigeria. If you get anything similar to this, DON'T SEND THEM ANYTHING.