I would like to submit designs for this but first please guarantee the project....

The project is now guaranteed.

Did I understood right: the smart phone is a "central" in your illustration?

It's just one idea. Feel free to go with a better one. The essential point is to have something clever that captures the attention of the recipient. My thought was that there would be some curiousity about what the text conversation was all about and in reading the dialog between the accountant and the business owner, the reader would get my message.

Before moving on a design, I'd be happy to review any concepts or ideas you have and giving more direction before you start on the design.

Hello, I have a question regarding the media of the postcard. Does it have to be a traditional one sheet of paper card, or could it be a foldable one. Since the idea you have posted is quite narrative I would like to know if the medium can me explored to make it a bit more interesting for the person viewing it.

I'll be uploading the finished postcard design to a website that prints and mails postcards. Here's a link to the postcard products, both folded and regular. The size will be one of the two smaller sizes. The regular (unfolded) is cheaper to print and mail, but if the regular size just won't work for your design, use the folded.

http://www.premiumpostcard.com/products

Thank you for the feedback.