Send one master checklist
Don’t drip-feed requests across several emails. List everything you need in one message, numbered, so the client can see the whole job and tick through it.
Give one place to send everything
A private link to upload files or reply, so clients don’t dig through email threads or remember a portal password. Everything lands in one place you can check.
Lead with the why
One sentence on how the documents move their project or deadline forward (“so we can file before the 15th”) makes your request worth prioritizing.
Keep a steady cadence
A gentle reminder three to five business days after the first request, then roughly weekly. Each reminder should mention only the items still missing, and get a little more direct each time.
Send during business hours
Reminders sent at 9am on a weekday get read and acted on. Ones sent at 11pm on a Saturday get buried.
Stop the moment a file arrives
Nothing annoys a client more than a reminder for something they already sent. Reminders should pause automatically for anything that’s in, and stop entirely when everything is.
Automate the routine, keep the judgement
Let software handle the scheduling and the “still missing” lists. Keep yourself in the loop for anything sensitive: price, scope or deadline changes. Follow Up With holds replies like those for your OK, and you can read every email before it goes.