Gmail now lets you star and label outgoing messages before you send them. This is a great new feature that allows you to organize messages right from the start.
It can also be useful to help you remember to follow up on important emails by labeling in a category like "follow up" or starring them. You can also do it in the sent folder after you have sent an email.
Educators could use this to organize sent emails by topic (parent communication, student issue, etc.) and then make it easier to follow up on emails that haven't been returned.