Should I review a paper that violates the maximum length limitation? I am reviewing a conference paper that violates the maximum number of pages by more than 10%. I believe that this is enough reason to outright reject the paper.

However, maybe the authors would welcome reviewer comments anyway. But I do not want to waste a day's work, in case nobody cares about my comments. What is customary and ethical in such a situation?
There is only one possible answer: Ask the Program Committee chair. It is an almost-one-line mail:


  Hello Jeffy,
  
  one of the papers I've got to review for the ABC Congress doesn't fit in the page limit given, it's: John Doe et al.: Study of DEF in context of XYZ, link:
  http://sciencesconf..../link-to-the-paper-in-the-review-system
  
  Should I still review it or is exceeding the length itself a reason for rejection?
  
  Cheers, Tom


It saves troubles in the thing I think. It may be fine in some conferences (when the page limit is taken loosely) and may be a problem elsewhere (when it's strict for instance because the proceedings publisher is strict about it, or for whatever reason). You can't know this, there's the PC chair to know this.