Let’s face it. Either I had too much fun in college or I have too much stuff going on in my life, I am forgetful! So, if you have something you can do ahead of time, why not setup a delayed send? These timers can serve all sorts of functions such as timing messages so that they see them when they arrive at a particular place, security so that you know a message will be sent while you are on vacation or out of the office, being able to setup email tasks ahead of time so that you can remove them from your to-do lists, and many other reasons.
It is completely uninstallable and does ask for a lot of access to your email account. It’s hosted on script.google.com and has many followers, so there it is likely clean, but I haven’t personally inspected any of the code, so I am not giving my stamp of approval. I did try to install this and test it, but it didn’t seem to work with my company email. I will try again with my personal email when some more time frees up. Enjoy!