That's what I do as well. I have my yahoo mail forwarded to my gmail so I have the convience of push and syncing both ways. Everyone still emails me on my yahoo and when I reply back I set gmail to reply as my yahoo and no one is the wiser. It is perfect. Plus even with IMAP with yahoo it wouldn't sync my yahoo folders. It brought the folders over but they were empty the mail I have saved in them on the web doesn't show on the phone. That is not the case with gmail. You get all that info.
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