Whether it’s a letter or an email it can be tough to know what’s appropriate to call someone when addressing them in written form. Obviously in person it’s much easier to clarify without offending them, right when you meet or when you end your conversation. The important thing to remember is: err on the side of too formal. Would it be horrible if you wore heels and everyone around you wore flats to a networking event? No, you’re just a little taller, and you probably have better posture. Anyway, especially with women it can be tough to tell how to address them – men have it easy, with Mr. there’s no qualifier as far as their relationship status or age.
One of the first mistakes people make is which gender a person is. Fortunately, the internet has afforded us the capability to stalk someone via linked in or maybe a company about page, where you can see a photograph or maybe identifying characteristics like being in a sorority in college, or being part of “Women @ X-company”. Be careful with unisex names, especially when communicating with someone for the first time.
For women, use Ms. if you’re not sure – it’s not offensive in today’s world, unless you’re absolutely certain they’re a Mrs.
Now about first names. This is a tough one, primarily because industry to industry and region to region you’ll find different levels of formality. Even different income levels. In middle school, I called all of my friends parents by first name. At my private high school it was always Mr. and Mrs. no longer how long I’d known them. Basically, unless they’ve explicitly asked you to call them by their first name, or you know them from a setting where you’d call them by first name, stick with the formalities. Another clue is in how they signed their email (how they address you will typically be your first name after the first time they write to you, since you’re a college student or young adult it’s appropriate). If they signed their full name definitely make sure to call the Mr. or Ms. Even if it is just their first name it can be tricky, but the full name in the signature is typically a big hint, whether or not they’re consciously thinking of it.
Any other situations I haven’t touched upon, comment below!