if your book cover is rejected by KDP, CreateSpace, IngramSpark, Barnes & Noble, Lulu etc.
and you are receiving something like
“Resize your cover so that the image or background on the cover extends far enough beyond the edge. Add an extra 0.125” (3.2 mm) on your cover. This prevents manufacturing issues when the cover is trimmed…"
I will got your cover approved by the relevant venue in a short span of time