I once sent the same sentence to two clients on the same afternoon.
"Just checking if you had a chance to look at this."
One replied in twenty minutes, apologised for the delay, and thanked me for the nudge. The other went quiet for four days and then opened his next message with "I have been busy, obviously." Same words. Same day. Same tone in my head when I typed them.
For a long time I assumed I had written it badly. I had not. I had written it identically, which was the problem.
Text arrives without a voice attached
When you say something out loud, the sentence carries a lot of freight that has nothing to do with the words. Pitch, pace, where you put the stress, whether you smiled halfway through. Strip all of that out and what is left is a bare string of words that the reader has to perform in their own head.
And they perform it in whatever mood they are already in.
Psychologists at Chicago and NYU ran a study on this in 2005 that I think about more than is reasonable. People wrote messages that were either sarcastic or serious, then predicted how often recipients would correctly identify which was which. They guessed around eight times out of ten. Actual accuracy was close to a coin flip. The senders were confident, the readers were guessing, and neither side knew there was a gap.
That gap is where most client trouble starts. Not in rudeness. In a neutral sentence landing on a bad morning.
Which means "write well" is not actually the instruction
This is the part that took me years to accept, because it undoes a lot of what school teaches.
There is no version of "just checking if you had a chance to look at this" that works on both of those clients. The first one wanted the nudge. The second one heard an accusation because he already felt behind. Better grammar would not have saved it. Politeness would not have saved it. The message needed to be a different message.
Good writing, in a client relationship, is not a fixed target you hit once and repeat. It is a moving one, and it moves per person.
Three things that vary, and how to read them
Most of the variation I have seen sits in three places.
Directness tolerance. Some people want the ask in the first line. Others read that as abrupt and need one sentence of runway. You can usually tell from how they open their own messages. If a client starts with "Hi Depender, hope the week is going well" every single time, matching that costs you nothing. If they start with "Re: invoice", stop writing warm-ups.
Warmth requirement. Watch the sign-offs. A client who ends with "Cheers" or "Thanks!" is telling you the register. One who ends with "Regards" and a full signature block is telling you something different. This is the cheapest signal available and almost nobody uses it.
Detail appetite. Some clients want the reasoning. Others want the outcome and get irritated by the reasoning, because to them explanation reads as excuse. Look at the length of their replies. Someone who answers in nine words does not want four paragraphs back.
None of this is complicated. It is just tedious to hold in your head for fifteen different people at once, which is why most of us do not, and instead write one house style and send it to everyone.
The test I use now
Before I send anything that matters, I reread it as the specific person receiving it, on their worst day of the month. Not on a neutral day. Their worst one.
If it still reads fine, it goes. If it wobbles, the fix is almost never adding an apology. Usually it is removing a hedge, or moving the actual point up to the first line so they are not reading three sentences wondering what I want.
That single habit has done more for my client relationships than any amount of vocabulary.
Where this leaves you
I am wary of advice that ends with "be more thoughtful," because thoughtful is not a technique, it is a mood. So here is something concrete instead.
Pick the client you are most careful around. Open their last five messages. Note the greeting, the sign-off, the average length, and how fast they replied. That is a profile. It took you four minutes and it will change how you write to them permanently.
Do that for everyone you work with and you have the thing I eventually got tired of doing manually and built a tool for. But the tool is optional. The observation is not.
The message is never the whole message. The person on the other end finishes it for you.