To facilitate sales through a lab, you have control over which products you wish to include in the price plan as well as what prices you wish to charge for these items. All invoicing is automatically managed for you so please ensure you have filled in all the correct data regarding your company and VAT status at My Profile -> My Finance Details -> VAT + Invoice Details.
You (and theimagefile) obviously want your customers to receive good quality prints every time so first lets just go over the few basic rules that you need to follow to make sure you and your customers receive a first class hassle-free service.
For automated print fulfilment, please remember that it is automated, so you need to ensure that you follow some simple guidelines:
Make sure you upload images in JPG format that are prepared to print quality.
Make at least one test purchase to satisfy yourself of how it all works from both sides of the site — your perspective and the customer's perspective. You will then have a full knowledge of the complete end to end service.
If you require help with aspect ratios just search Aspect ratios for print sales in the Information area. You can also view the aspect ratio of any of the images you have already uploaded in from the File Information page...
...or a detailed view of all your images, by clicking the link "Calculate the aspect ratio of your existing images" in the price plans page.