Thank you for the message! I am happy to provide test translations to potential clients. I understand that this is a test translation, that I will not be paid for this work, and that it does not guarantee that I will ever receive paying work from you. I know how important it is to verify that the people you work with can perform as promised.
To that end, while I'm working on the test translation, there is something that I need you to do. In order to ensure that clients can meet payment deadlines and that there will be no problems with the chosen payment method, I require a test payment from all new clients. To make sure that your account has not been flagged by the chosen payment service the test payment will need to represent a reasonable sum of money. Please send US$600 to my account before the end of the business day tomorrow. (This test payment is non-refundable.) My payment information is included at the end of this email.
I'm sure you will understand why such measures are necessary.
I look forward to working with you!