Hi,
Can you explain a little about why you need to do that? It'd make suggesting an appropriate solution easier.
It seems like a slightly strange thing to do. Most webmail providers also provide SMTP/IMAP access. In fact, all the ones I can think of do (although I don't know about all of them of course)
Parsing email from a web page would be clunky and potentially unreliable - small changes to the web page could easily break anything you got set up. Wouldn't a better approach be to set up Mail to access the account and then maybe use Automator and/or AppleScript to save messages (if necessary)?