Getting to the top of your email list isn't so obvious on the iPad 2, though it is easy: Tap the top of the screen. On the TouchPad, there is no fast-jump capability.
The message text is quite readable on both tablets, and both let you use gestures to zoom in and out.
Email management. Both devices support multiple accounts and universal inboxes. I prefer the way the TouchPad provides all the accounts in one place, with universal inboxes at the top of your accounts list (the Favorites area), compared to the iPad 2's duplication of its accounts list in a separate pane: one set for universal inboxes and one for their folder hierarchies. I also like the TouchPad's ability to add specific mail folders to the Favorites area.
The iPad 2 has a message-threading capability, which organizes your emails based on subject; you click an icon to the left of a message header to see the related messages. That adds more clicks to go through messages, but finding the messages is substantially easier. (The iPad's iOS 4 lets you disable threading.) The TouchPad has no equivalent. It does lets you flag emails, but to see flagged messages in one place, you have to enable All Flagged in the accounts preferences.
On the TouchPad, attachments are indicated in a bar below the subject. If you have multiple attachments, tap the indicator bar to get the full list. Tapping an attachment downloads it (be prepared to wait a second or two for the download to commence). Which app opens a file depends on which app registered it. Unlike on the iPad 2, you can't choose an alternative app or set the default for opening a particular file type on the TouchPad. On the stock TouchPad, PDF files are opened by Adobe Reader, Microsoft Office and text-only files by Quickoffice, and images by a preview window that lets you save the image to the Photos library.
The iPad 2's native Quick Look viewer handles a nice range of formats -- Microsoft Office, text-only, PDF, various images, and Apple iWork -- and it opens attachments with one tap, downloading them if needed at the same time. Using iOS's Open In facility, you can also choose which app to use instead of the default by tapping and briefly holding the file attachment -- the way it should be.
Shockingly, neither the TouchPad nor the iPad 2 -- still! -- opens Zip files. On the iPad, there are several third-party apps such as the $1 Unzip, $1 ZipThat, $2 ZipBox-Pro, as well as the $5 GoodReader file-viewing and management app. But there is as yet no unzip app for the TouchPad.
Both the iPad 2 and the TouchPad remember the email addresses when you reply to a sender, adding them to a database of contacts that's automatically scanned as you tap characters into the To and Cc fields. Both devices let you add email addresses to your contacts list by tapping them.