why am I only get part of my emails?!?

I have a form that is 3 pages long on my site.  Once they click the "next" button on the first page, it automatically sends the page to me then advances to the second page.  Same from 2nd page to 3rd.  For the last week I haven't been getting all of the pages all of the time?  Sometimes I get page 1; sometimes page 2; and sometimes both?!?!