The iPad's native Mail app cannot read MIME and uuencode mails. The workaround is to use Safari and webmail from your iPad. I'm not aware of any mail app that can handle these formats.
I use an App called Docs To Go. You can save all your PDF's and other Docs in this App. All you have to do is open the file and there is a send button on the bottom left side. Works great for me. Hope this helps.