in his email he says :

Please reply by 3 pm today so we can confirm with the client.

in my experience when an action relies on somebody 'coming back' ESPECIALLY if it's a client. (do you want this, or that?)

It's best to tell them what you are going to do, unless they confirm otherwise.

e.g. We will proceed with removing feature Y to meet deadline of Mar 19, unless otherwise directed by 3pm today.

This avoids the limbo situtation where a team can't progress because they don't have clarity on X or Y.

Not always applicable but I find it works a lot of the time.

After sending emails to suppliers, they would often answer the first point in the text but ignore later points. This speaks to the send only 1 thing in an email, but if you have a few questions about something then put them in a numbered list.

I found response quality went way up when i did this, and often the responses were along the lines of :

1. do this 2. yes that's right 3. ok we note that

which i'm sure helps them becuaes the email is easier to read and parse in the first place and easier to write a reply to.