I have suggested to allow mail account to download all mail from Hotmail or yahoo mail so they could keep all the old mail they have in new account.

I just have one more thing to add to that. ( but don't know if that is technically possible)

To check for any new email they have in their old account either by having coloum saying you have three mail in your hot mail account and 2 new mail in yahoo...etc
or actually have it downloaded to the new Gm account everytime a new mail in the old account ( Hotmail or yahoo )has arrived.

And one more thing. People tend to have chain mail and header ( where all email address have been sented to ) of the mail tend to be very long and wasting storage space. Is it possible to have a funtion if the mail header > then set amount then the mail header would be deleted. ( Mail header only!! )

And finally, a payment system as plug in or something??