I am using a pop mail account.
When downloading e mail on iPad, some messages, i can see who sent the mail, but the message is not downloaded.
Sometimes, the button on the bottom of the page allows me to download the rest of the message, but very often, the button gives 0 Bytes to download.
My iPad mail settings are : e mails are downloaded, but not removed from server.
On my computer, in Outlook, i can read my mails without problems.