When I look at a submission my first decision is whether I think it would be productive for the manuscript to go through the peer-review process, or whether it should be declined without review. It is the cover letter that gives me the information I need to make this first important assessment (or at least it should). If I believe the manuscript merits review by JM3, my next choice is which senior editor to send it to, based on a match of editor expertise to paper topic. The senior editor will then repeat my exercise, deciding whether to decline without review, and if not, which associate editor to assign it to. Finally, the associate editor will again read the cover letter and could again decide to decline without review. If the associate editor believes the material merits review, he or she must find the right reviewers for the manuscript. Each editor might look at the full manuscript, and may even read it fully and carefully. But it is the cover letter that is the first and most important indicator that each editor looks at when making these decisions.