There are 2 ways to share your iPhone pictures via email or MMS but one is better than the other because it does not compress the images and keep them in their original size and resolution.
Method 1: The first way is to simply go to the photo application and type “share”. This will ask you if you want to share via email or MMS. Whatever you decide, it will compress the picture to 800×600, reducing the quality of the image.
Method 2: The better way to do it if you want to preserve the quality of your images is to “copy” (not “share”) the image, then manually launch the mail or MMS app, and paste the image into it. This way, your images will not be automatically resized and should be 1600×1200.
By using the second method, your MMS or email will take longer to be sent out, but at least it will be a full quality image.