Q. I found nothing in the Manual regarding this, and maybe there is no actual standard on this topic. My English-speaking colleagues capitalize the word following “Dear” in a group letter—for example, “Dear Colleagues,” or “Dear Teachers.” Is the capital necessary? Thank you for your help.
A. You’ll still find “forms of address” in the back of printed editions of Merriam-Webster’s Collegiate Dictionary. And though the purpose of that section is to help you address someone like a pope or a judge with a traditionally proper, respectful formula, you can glean an answer to your question there. Words that would otherwise be lowercase—like “sir” and “madam”—are capitalized in an address: “Dear Sir,” “Dear Madam.” For one thing, these words stand in for a person’s name. And capital letters are generally more formal than lowercase, making them a natural choice for something as conventional as the greeting at the head of a letter or email.
The Gregg Reference Manual, which specializes in business documents, confirms this choice. For a letter to more than one person, the tenth edition (published in 2005) advises “Dear Friends (Colleagues, Members, or some other appropriate collective term).” So unless you’re being casual—or writing according to a tradition where lowercase is the norm—prefer capitalization for words like “Colleagues” and “Teachers” in your salutations.