Some publications accept unsolicited submissions only during specific time frames such as the school year. Cover letter requirements. Some publications like to receive a biography, whereas others don't care. Some like to know previous publication history, whereas some prefer not to know. Comments on rejections.
Some editors comment on rejections.
For example, is your name and address required on each page, or is centering off limits, or is there a specific word or line count, or should you skip a space between verses . . . Finding the Guidelines You could write to the specific publisher requesting their submission guidelines. Books like the Writer's Market, Poet's Market, or The Canadian Writer's Guide give up to date information. Numerous print publications have websites that supply their guideline information or provide an e-mail address, where you may request their requirements. That would depend on your writing and how you want to write.