This one is trivial. When you get an email directed at you, reply.

It’s a total no-brainer, right? Why mention it at all? Let me give you an example.

Partner sends you an email:

“Hi KC, notes on your deck attached. Please send me the update by 10am tomorrow morning.”

Your response?
Getting to work, being the good consultant that you are. After all, the briefing was crystal clear, you have all information you need and it better be done in the morning. No need for another email, you start cranking.

*ping* – That was the fictional sound of your inbox, at 6pm. Another email from said partner.

“Did you get the notes I sent?”

Which translates into: “I haven’t heard from you, so I have no idea if you are working on this or not. If you are not, I have to get you on it asap (and give you a stern talking to on priorities). If I still don’t hear from you, I will have to engage panic mode and give the work to somebody else to make sure it is done by 10am!”

Fuck.

That sure wasn’t what you wanted the partner to associate with you, right? After all, you have been slaying away at the edits for a few hours already!
Unfortunately, the partner has not the slightest idea and instead started worrying.

This is just one of many scenarios where you can get caught by the same effect:
THINKING something is not the same as COMMUNICATING it. You sure thought “I’m on it!”. But the partner didn’t hear that.

Simple solution: Just reply with a quick affirmation. “Thank you for the notes, I’m on it and will get the update to you by 10am tomorrow morning.”

Bonus points: Before you send that reply, actually open the document/read the whole briefing/ check the whole input. That way, you can make sure to ask follow-up questions immediately or catch the occasional referenced attachment that did not get forwarded.
In short, make sure that when you say „it will be done“, you make sure that it can be done.

As I said. This one is trivial. Now go and do it every time.