Help the editors appreciate the significance of your work.
Although it is unethical to submit your paper to multiple journals simultaneously, this is allowed for these inquiries.
This can save you time by having editors tell you that this is not a subject that they would publish, and for the one with the most positive feedback, you have them anticipating your submission, which can make it stand out from the competition.
Explain why you decided to submit your manuscript to that particular journal.
Why would your paper be of interest to the readers of that journal? Explain which section of the target journal would be most appropriate for your manuscript (e.g., Original Articles, Brief Communications, or Reviews).