There can be a couple of reasons for this. If you have a slow Internet feed and also it can depend how a message has been sent. If you scroll down to the bottom of the emails do you see a download tab to download the rest of the message?
I've moved your thread to our Help Section where you will receive a better response.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.