Emailing is one of IT's greatest inventions, but it does have its own problems. One is that it is hard to differentiate between emails that need to be answered and those that don't. Especially if there are long-term deadlines, like "Please reply within 1 month," which tend to get lost in ever-overcrowded inboxes.
You may want to consider a general request workflow.
It is absurdly simple yet surprisingly useful. The request stays in your to-do list so you can easily make the deadline.
You may notice there is no option of canceling or ignoring the request; that is, theoretically it is possible to get caught in an eternal loop between Task 2 and 3. You probably won't mind eternal messaging with a friend, but if the request comes from that colleague who's not exactly your favorite person... or, to be practical, if you are told to ignore the request and you don't want the process to go through Task 3, you'll want a way out.