If you receive pictures uploaded from the FotoWeb Desktop uploader for Windows and Mac you can turn on a feature in the archive settings that enforce client-side conversion of all pictures to JPEG before upload. Not only can this be cost-saving when uploading files over mobile networks, it can also be an effective way of ensuring format consistency in your workflow.
To make sure all pictures uploaded are converted to JPEG, open the archive's properties and go to the Export and Import tab. Then tick the option to Convert all images to JPEG before upload in FotoWeb Desktop. You can set a compression quality, 100 being lossless, and optionally choose to restrict image size (uncompressed) and/or file size (size after JPEG compression).