If I forgot something, it probably wasn't important.

https://startrek.website/post/1897069

Gmail is so nice because after it's done scouring through my potentially private emails it lets me know if I said "is attached" but didn't attach any files
I also like the “undo send” button. Saves me all the time at work.
The only drawback is how long your onosecond is. If you have a very high onosecond, the undo send button can’t help ya.
many, probably most, email clients do this