Can we delete our messages?

I have 4 yahoo emails and one gmail account. Yahoo account is awesome because of the new Yahoo beta. The best thing is you can open different emails in tabs and play around them. But yahoo gives creeps too as after sometime it automatically starts generating lots of spam. Gmail is good in this case. The best thing in gmail is once you start an email with a person, it records all the further emails attached to it. So if ihave to find a particular email from my honey, i have all of them at the same place. In yahoo I have to scan thorugh all the emails. I also have a hotmail account but this Bill Gates takes everyone for ride either it is hotmail or one of his windows gourmets. Do you know some new email, let me know. If I get one next time I will let you know.