Just to share with you what i discovered. Sorry if you already know the trick !!!!

Suppose you want to follow an email for example something you are waiting for. Just drag the email directly from "mail" into the text window under the task. A link is created and then if you have t use it just click and magic you mail is open !!!!! Congratulation to the omnifocus team this is absolutly great !!!!! :)))
I am so happy !!!