Cover letter, when publishing in a journal

Question

How to write a cover letter to journal, when submiting manuscript?

1. In the letter, it is expected that I propose 5 referees. Is this the only reason to write a cover letter?
2. Will the cover letter be sent to the referees? Or only to Journal's staff.
3. I feel reluctance to praise my contribution in the cover letter. The article should defend it itself. Is the praising important part of the cover letter? Is it required?

Answer 1

1. It is also polite to write a cover letter, even if nobody asks for it. And the purpose is often to ease the process of finding the referees, so helping to do so by giving insights about the paper that cannot be write in the paper is a good thing.

2. If you mention potential referees, I guess it will not be sent to the chosen referees. Otherwise (in my experience) it is.

3. You don't have to praise your results in the cover letter. Just state shortly the results (say more than the abstract, less than the introduction). If you think that there are issues related to the paper, this is also the place to state them (conflict of interest, new way of considering something - which can hurt someone's feelings -, direct negative comment on related work, etc.). If you think that, because your paper is gap-bridging, you need reviewers from several fields, you should say it as well.

Answer 2

1. Sometimes it could be. Sometimes one has to explain some prior publications and how they relate to the current manuscript.

2. Usually, the cover letter is not sent to reviewers.

3. Brief statement should be fine. It is not not required.