If you don’t already have a “waiting for” folder in your email, you need one. This is the folder I keep in my email where I drag sent messages that I’m waiting for a response on. I go through it basically daily, and it’s fascinating to see how often I haven’t heard back about something and need to follow up on it, and which I otherwise might have forgotten about until the lack of answer popped up as a problem. I do this not just for work emails, but personal ones too, like the person in my homeowners association who was supposed to get me an answer to a question about dues but didn’t, or any other question that I need the answer to but might otherwise forget that I’m waiting on until months later. Yes, this does make me the annoying person who will follow up with you when it’s been a week since I emailed you a question and I haven’t heard back. It also makes me the person who gets the answers I need and doesn’t discover weeks later that some crucial bit of info never arrived.