We recommend submitting a vector file for any print order as it produces the most optimum results. Although not necessary for all print orders, there are some special orders that do require vector files:
Rubber Stamps artwork
Tissue Paper artwork
Die-line files for custom shapes
Files for Foiling
The following files are highly recommended to be submitted as vector, but can be produced with high quality raster images when needed:
Separations files for Spot Gloss
See: What is a vector? What is the difference between a vector and raster file?