Can iphone get hacked

I received an email from a friend, it contained a subject, but when I opened it the email was blank. I was accessing my email through the mail app on my phone, and was not connected to WIFI at the time, I was running on 3G.  I suspected he did not send this email, so i immediatley alerted him.  Then after a few minutes I realized I should delete the email, which I did.  My Question here is, was it possible for my phone to get hacked after opening the email? there was no link in the body of the message, and I know not to click on them.  I changed my email password, and my apple ID password, I just wanted to make sure there was no way for this email hacker to get into my phone and steal information just because I opened the email.  resopnses would be greatly appreciated!!