Future Me - Send an email to your future self
Chars - Unicode Symbols Keyboard for iOS
Dabble Me - Your own private place to write. A journal/diary to help you remember what's happened in your life.
Smart Compose in Gmail - Write emails faster with Smart Compose in Gmail
Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.
EasyEmail - Gmail plug-in that helps you write emails quickly