The purpose of a question can off topic (for example wanting a way to solve a computing problem) while the question itself can be on topic (the person who knows the computing answer can be reached through a postal mail using only the First 4 letters of the alphabet so how to do you make someone aware you want to ask them a question using only the first 4 letters of the alphabet)?
In that case, should the post whose purpose if off topic be closed or should it be left open as long as the question itself is on topic?