Guys, there are no virus/malware in apps or emails on the iPhone. The app store controls all apps and checks them before they are ever released for public download. As far as emails if you have an account that is hacked/is sending spam It's coming from your mail account on the SERVER not your iPhone. You need to contact you ISP to get it taken care of.
That's not entirely true! You can get viruses very easily by installing apps, packages or system tweaks from Cydia. I recommend not entering any strange repo source into Cydia and then install any apps, packages or system tweaks that you have not researched about because for all we know, they could be easily infected by viruses and what is even more dangerous is the fact that Cydia allows packages to have access to the root directory on your iDevice which is all the virus needs to destroy your iPhone's hard drive. Community Sources and Repositories already on Cydia will most likely be safe to install from, However even they are not 100% safe because anyone can upload a package to these repos and depending on how busy these repo owners get may determine if they check each and every package that comes through their repos. I strongly advise that you be aware of what your installing from Cydia.