We've created this Forum Thread with some workarounds and advice to assist you in publishing you ebook.
Total File-Size for Projects:
The total file-size for a Lulu project cannot exceed 1 GB. This is a problem, because when you download the USLetter.zip template file, as I have, the files within them, 8.5x11_Back_EN.png and 8.5x11_Front_EN.png, result in 35 MB per page for images placed over those templates. So I opened 8.5x11_Front_EN.png. Then I opened as layers all the odd-numbered pages and overlayed them on top of that template. When I went to save each layer individually as a png, the resulting files were 35 MBs each. There are unattractive ways around that: I could save it as a jpg, losing detail and pixels. I could use compression for my ongs. That would also lose details and pixels. And, I could not save the gamma for each image. That is equivalent to saving the image without alpha data. Or, I could change my images from 300 ppi, which is certainly a no-no for print images. Long story short, LuLu should not provide a template, that when used forces tha client to either lose quality for thier book, or be in violation of the 1 GB limit.