When is it appropriate to consult with the publisher/editor prior to manuscript submission? Motivated by the answer written by @ÉbeIsaac to this question: Can I write a paper on a method that is novel but yields similar results compared to existing methods?

This participant wrote


  Also make sure you go through the Journal guidelines and consult with
  the publisher/editor prior to manuscript submission.


The part that I would like to understand better is consult with
the publisher/editor prior to manuscript submission.

My question:

When is it appropriate to consult with the publisher/editor prior to manuscript submission?
This really depends on factors such as the field, the reason for contact etc. In my experience it is usually appropriate to consult with the publisher/editor in two cases, when:

(1) you have a short question about something that is not answered in their submission guidelines, or;

(2) you would like to send them an abstract to determine whether they think the potential submission fits with their journal.