While this is unusual it is not uncommon.
In today's day of advanced spam filtering, what qualifies as spam is a very broad definition. Some systems simply see an email from a company that you haven't done business with before and automatically assume it is spam.
We recommend first: check your spam folder. If your receipt isn't in there, then double check your Trash folder. Some mail providers skip the spam folder and dump it straight into the trash.
If you still can't find your receipt, then please submit a new ticket and ask one of our reps to confirm that the email address on your order was entered correctly. They will be able to adjust your email address and resend your receipt.