Hi,
-Which model iPhone?
-Which version of iOS?
-Who/what is the source of the emails?
-Do you have the same account setup on a Mac or PC, and does your email provider have webmail access?
You should be able to simply tap them to load the remote image, depending on the size of the file. You may need to check your settings for email on your iPhone, to see if Load Remote Images in enabled.
C