I'm moving from yahoo mail after being with them for 10+ years. I have their plus service, so I can use pop/imap to move my messages (and my current ones are being forwarded now). My problem is that I have a LOT of email I want to move, and I know I can download it all to outlook (which I pretty much have) and just move it over that way, but I have a bunch of filters that filter my mail and was wondering if there is some automated service that will forward my mail so the original senders are preserved and then the filters could just move everything automatically.
It depends on whether if fastmail support one of those things:
in this case, you can setup your old and new email accounts on a new email client, like thunderbird, and move all message from one folder to another.
Receiving mail using pop3 from an external account:
Gmail support this, it can be setup to download messages from another email account, not sure about how fast mail would support such thing.