Don’t put a “no” response back to some in the written word. There are many, many reasons for this but here are my top ones.
First, have the courage to say “no” to someone in person, or at least over the phone/video chat. They deserve to hear it from you directly and in your own words.
Second, when you do say “no” in person, it is generally going to be received better than in text and if it isn’t you have a chance to further explain yourself and answer questions and generally make sure they understand why you said “no” to begin with. Also, in this conversation, if you can get your point across they are more likely to take “no” for an answer and more likely to not have hard feelings about it.
Third, email can be forwarded to 1 person and 1 million people. Do you really want your “no” response seen by the world? If not, don’t send an email.
Forth, emails (and text in general) can be saved, referred back to, and ruminated over. They don’t have as much of a chance of being forgotten or at least fade into distant memory. So, if saved, your “no’s” can come back to haunt you. “See, look what you said about this 7 years ago, you were a jerk then and you are a jerk now!”
Fifth, (and this is a big one) unless you’re going to use lots of emoji, people can read into your words all kinds of tone that you didn’t intend. As a human being, it is very hard not to do this. We all do this. We naturally want to understand the emotions behind the words. And you can’t get that from the standard way people write emails today. EVEN IF YOU USE ALL CAPS or lots of !!!!! (which you also shouldn’t do) you are only showing emphasis and not emotion.
Are there exceptions to this rule? Absolutely. You have to pre-judge the importance or gravity of the conversation in which you would be saying “no.” If you’re just going back and forth with a friend about where to eat for dinner, then it’s probably okay to say “no, I don’t like that one, let’s try this one.” However, if you’re saying “no” about your time, your energy, your commitment, your funding, your engagement, et cetera, then pick up the phone, tell them you need to have a talk and don’t put it in writing.